Again, I'll go slightly off topic to attempt to make a point. If someone teleported right next to a Wizard and made an attack, would the Wizard get to use his reaction to cast Shield? Of course he would you say. Uh but, why? The rules don't even say you have to see the attack coming. What if the Wizard is blind or just a blinfolded character? Don't matter, RAW says he can do it. I mean, this ability actually says you get hit by an attack...then you turn back time shaking your finger, nuh uh u ain't hit me. LOL, and I love Shield!
To my mind, this is a much more extreme show of power than just letting some polearm bro get an AoO at 5 ft instead of 10 ft. If this is an apples to orange comparison for you, I understand. The purpose is to yet again call out RAW when you just blindly follow it or try to, it isn't always consistent or logical.
That's fine if you want to play it like that. Take it to the homebrew forum. This is the Rules and Mechanics Forum. RAW is important for the Rules and Mechanics Forum. Just because people argue for RAW doesn't mean that they always agree with RAW. Shield works exactly the way that you mentioned in your example RAW mechanically. The Narrative description will be different, but mechanically that's how it works. Mechanically, the polearm bro doesn't get an OA at 5 ft unless the bro is also a Cavalier or is using the UA Tunnel Fighter Fighting Style (which is the spiritual ancestor of Cavalier and won't see life in an official WotC book in that form).
Polearm Master: While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.
Opportunity Attacks
In a fight, everyone is constantly watching for a chance to strike an enemy who is fleeing or passing by. Such a strike is called an opportunity attack.
You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.
You can avoid provoking an opportunity attack by taking the Disengage action. You also don't provoke an opportunity attack when you teleport or when someone or something moves you without using your movement, action, or reaction. For example, you don't provoke an opportunity attack if an explosion hurls you out of a foe's reach or if gravity causes you to fall past an enemy.
The general rule states that you must see the creature move out of your reach. PAM adds that you can make an OA (which requires that you see the creature) when they enter the reach that you have with that weapon. Whichever weapon you are using to make the PAM attack determines the reach, and you must still be able to see the creature to make the OA otherwise PAM would have told you differently since the general rule is that you must see the creature. Creatures that enter your reach that you don't see don't provoke OAs because you don't know that they are there until they are within your reach. (Does that necessarily make sense? Not always, but hey magic is cool, so let's keep that but forget this other stuff because it's not cool for my character). You get to attack the creature normally later. If you want to make the attack against a teleporting creature, use mage slayer to use your reaction to make an attack against the caster (not an OA by the way).
If the DM is adjudicating the game in a way that makes it unfun for you, have a discussion with them. If they decide that they agree with you, awesome. If they explain their position in a way that appeases you and you want to continue with the character, awesome. If they don't explain their position in a way that appeases you, ask if you can rework the character in a way that will fit the game that is being played, ask to make a new character, or find a DM that does agree with you.
Again, I'll go slightly off topic to attempt to make a point. If someone teleported right next to a Wizard and made an attack, would the Wizard get to use his reaction to cast Shield? Of course he would you say. Uh but, why? The rules don't even say you have to see the attack coming. What if the Wizard is blind or just a blinfolded character? Don't matter, RAW says he can do it. I mean, this ability actually says you get hit by an attack...then you turn back time shaking your finger, nuh uh u ain't hit me. LOL, and I love Shield!
To my mind, this is a much more extreme show of power than just letting some polearm bro get an AoO at 5 ft instead of 10 ft. If this is an apples to orange comparison for you, I understand. The purpose is to yet again call out RAW when you just blindly follow it or try to, it isn't always consistent or logical.
That's fine if you want to play it like that. Take it to the homebrew forum. This is the Rules and Mechanics Forum.
That's not homebrew man, that's his interpretation of the Rules. And his interpretation belongs in this forum just as much as the people who like to argue RAW all the time. This sub is called Rules and Mechanics, not Rules As Written. It's for discussing the rules of the game and sharing how you apply those rules... not telling people to get out because they don't think like you - that's what Facebook is for, and there's no need to bring that kind of cancerous and toxic shit in here.
Sometimes I think people trying to interpret RAW forget that you can still use common sense. I feel like the rules were written with the underlying assumption that most people would use common sense and not take things in the most literal mechanical way so as to not require every little detail possible to be included in the description of every spell, ability, etc. If I have a crossbow that can shoot 80 ft but, I'm in a 20 ft room, obviously my range is now some fraction of that depending on where I am standing.It would be the same thing for a reach weapon that has it's reach obstructed. You have a max range and an effective range which is circumstantial. Okay, call that Homebrew, I'm sure you will.
Now for some more common sense. You can't AoO someone who teleports away because they simply aren't there anymore. If someone teleports to you, I would think that this scenario reversal doesn't play out the same way.
Sometimes I think people trying to interpret RAW forget that you can still use common sense.
Common sense is useful for deciding what is RAI. It's not relevant to RAW -- RAW is strictly about textual analysis. Which does mean a lot of rules discussions don't have any final resolution because RAW is not clear.
Yes, that is actually a better way to capture what I mean, RAI is just an opinion though but, hopefully correctly determined with common sense.
The thing I find most amusing is no one calls this a rule exploit. Usually some power gamer comes up with a RAW argument that can't be disproved and unbalances the game unfairly to his advantage. I don't see this topic any differently except it happens at the expense of the player instead of to his benefit.
Sometimes I think people trying to interpret RAW forget that you can still use common sense. I feel like the rules were written with the underlying assumption that most people would use common sense and not take things in the most literal mechanical way so as to not require every little detail possible to be included in the description of every spell, ability, etc. If I have a crossbow that can shoot 80 ft but, I'm in a 20 ft room, obviously my range is now some fraction of that depending on where I am standing.It would be the same thing for a reach weapon that has it's reach obstructed. You have a max range and an effective range which is circumstantial. Okay, call that Homebrew, I'm sure you will.
Now for some more common sense. You can't AoO someone who teleports away because they simply aren't there anymore. If someone teleports to you, I would think that this scenario reversal doesn't play out the same way.
The reason for RAW is for balance. This is a game after all. If an DM wants to rule outside of RAW because that's what fits their game better, that's how it should be played. If a DM wants to follow RAW because that eases the burden that they have placed on them, then that's how it should be played.
Saying that a reach weapon can't take an OA at 5 ft is a balance issue that the developers placed in the game. Interpreting that you can't OA a creature that teleports in is a mechanical balance effect that follows RAW. If we think of an OA as something that just barely happens on the reaction (because of the fact that it happens just before the target leaves your reach, then it would make sense for the PAM user to be watching the approaching character and making the attack when they come in. If they can't see the character come in because of burrowing or teleporting, there would be a sense of surprise that they showed up particularly if the PAMist is watching other things happening and focusing on that.)
For that matter, why should the PAM player be the only one that gets the OA coming into each? Mechanics. Why should the PAM player get the bonus action and not the longsword player? Mechanics.
I'm not arguing the threatened areas, I'm arguing the reach or in the case of your crossbow example range. Your range doesn't become hampered permanently when you enter a room nor does your reach become 5 ft or 0 ft because you stand next to a wall. If those were the case, I'd see a reason for your OA to go off while the creature was still in your "Old" range. But it doesn't work like that.
Yes, that is actually a better way to capture what I mean, RAI is just an opinion though but, hopefully correctly determined with common sense.
My common sense says that popping up inside reach shouldn't draw an opportunity attack from PAM; it represents what seems to me a perfectly plausible situation. NightskyPirate I assume has the opposite opinion. Hence the problem with 'common sense'.
Threatened area is not a thing in 5e. And RAW, Reach itself is not defined, it merely says that most creatures have 5' reach.
When something enters reach is determined by the GM, that is not defined by RAW. I'm acknowledging you can be right by the fact that the rules doesn't define what Reach is, which I'm gonna say again, Reach does not reach through things.
Yes, that is actually a better way to capture what I mean, RAI is just an opinion though but, hopefully correctly determined with common sense.
The thing I find most amusing is no one calls this a rule exploit. Usually some power gamer comes up with a RAW argument that can't be disproved and unbalances the game unfairly to his advantage. I don't see this topic any differently except it happens at the expense of the player instead of to his benefit.
That's actually the point that I've been arguing. That you are using this as an exploit that benefits the player because the rules don't say that you can do it that way. You're interpreting the rules one way. I'm interpreting the rules another way. By extension, everyone in this thread is doing the same thing.
It's clear to me that the way that I'm interpreting it is correct. You seem pretty adamant that your interpretation is correct. That means there is an impasse that won't be resolved until we're in a game together and the DM rules in favor of one side or the next. The following DM might be rule the other way or might be of the same opinion. SAC might even have clarification, but that won't change what is written (though I consider it carefully since I'm usually relying on the rules for structure and knowing the intent matters to me).
The RAW is very shaky, the RAI is clear as hell, and PM is still better than any other feat even when interpreted as unfavorably as possible.
If that were true, the debate would have died a long time ago.
On the contrary, these debates only tend to go on when there is a tenuous, shaky RAW interpretation that someone very strongly believes in which contradicts common sense and RAI. I admit that the RAW is not 100% clear because the Reach term is used in two different ways - 1) to determine what you can hit, and 2) to determine a boundary that triggers OA's and other reactionary attacks such as the one from PM.
A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.
Total Cover is equivalent to being behind a wall, if a creature behind a wall was standing next to me he is concealed by the wall which means
1) he does not provoke opportunity attack "You can make an opportunity attack when a hostile creature that you can see moves out of your reach." - PHB Opportunity Attacks (Using DnD Beyond)
2) Even if not using PAM, if you wanted to target this creature with a melee attack, you would have to move into reach, which would mean moving around his total cover.
Your reach does not extend through solid/impassable objects, even if the target is within 5ft behind a solid wall you may not attack him through the wall.
Notice how when discussing melee attacks the word "reach" is used and not "range". This is to highlight the difference between being in range of someone (spell) and being in reach of someone (melee attack). The creature can be within range but not within reach.
This is further demonstrated in spell attacks:
Inflict Wounds: Range/Area - Touch "Make a melee spell attack against a creature you can reach."
VS.
Firebolt: Range/Area: 120ft "You hurl a mote of fire at a creature or object within range. Make a ranged spell attack against the target. On a hit, the target takes 1d10 fire damage."
Sidenote: If you're going to make the argument that this is grid combat, then please refer to
Diagonal movement can’t cross the corner of a wall, large tree, or other terrain feature that fills its space.
" was 5 feet away from the a corner and a creature came around the corner. " From the OP's post.
If the argument is made that being around the corner is full cover, then anything behind that corner is concealed and thus unable to be attacked/targeted and thus not inside your reach.
I don't believe that definitively says that full cover restricts reach. In other words, those that say reach does extend through full cover would not be wrong because of those cited rules.
I do believe it is the correct interpretation, of course... just saying I think the folks who want to stick by PAM not provoking should be able to say they aren't going against RAW. I believe RAW doesn't specifically back anyone up here. Though I really think reach does work in the way prescribed above by snowboon.
Right, the problem with "Reach"/"Range"/"Touch" is that there aren't any book definitions of these terms (Aside from Reach being a property of a weapon) so I was using context clues in the book to help define the term. Because if you do a strictly RAW then you can't infer one way or the other that terrain blocks or does not block reach, but using context clues such as Inflict Wounds you can gather than you need to make contact with someone/something. Terrain such as a wall or door would obviously block contact and the spell wouldn't even fail as you wouldn't be able to cast it because you have no target. (Total Cover)
If you wanted to punch someone behind a wall you would have to punch the wall or move around the wall. The DM could also rule that you can punch through the wall and hit him, but that is purely flavor/DM discretion.
Now for some more common sense. You can't AoO someone who teleports away because they simply aren't there anymore. If someone teleports to you, I would think that this scenario reversal doesn't play out the same way.
I mean if you wanna bring in world logic into this, someone teleporting right next to you would be extremely difficult to anticipate. Also, Polearm Master is arguably trying to translate the advantage that a polearm provides in the real world when fighting an opponent with much less reach - there's a significant distance they have to cover before getting in hitting range where you can hit them and they can't hit you back. If someone teleports next to you, they've avoided that dangerous situation and whatever edge having that extra reach produced is lost.
Granted, that kind of reach advantage is also present with other weapons (e.g. a rapier vs a dagger) but D&D combat has to be streamlined, work in both 1v1 duels and group skirmishes, and polearms exploit that advantage to a greater degree than most other weapons in typical usage (pikes and halberds are extremely long.)
Anyways on the topic of reach and cover, this thread is super long so I might've missed something, but Jeremy Crawford did rule once that your reach does not extend into the wall or floor. And in my opinion that's the only sensible way to do it; I'm gonna be contrary here and say burrowing monsters aren't intended to get away scot-free. I don't care how good at burrowing the monster is, turning your back on an opponent to dig downwards is a bad idea and there's no way they can dig through solid ground faster than other enemies can jog away from you. You could sensibly make exceptions for special monsters like ghosts and earth elementals that don't dig so much as phase through things, but those are much rarer and already have special traits to account for their unique movement. Also there's not much of a point in declaring that your reach extends past a glass wall and an enemy beyond the wall provokes since you won't be able to target them with the attack anyways.
Anyways even if you rule that going around a corner into total cover counts as leaving reach and warrants an opportunity attack I don't think anyone's brought up that they should have 3/4 cover in that situation so I don't think it's a big deal either way. The same would be true if someone was going the other way into the reach of a player with Polearm Master: the OA would be provoked while most of them is still behind cover. So it really comes down to "no attack" vs "attack that's unlikely to hit", which doesn't seem worth debating to death to me. Go with whatever outcome you prefer.
Now for some more common sense. You can't AoO someone who teleports away because they simply aren't there anymore. If someone teleports to you, I would think that this scenario reversal doesn't play out the same way.
I mean if you wanna bring in world logic into this, someone teleporting right next to you would be extremely difficult to anticipate. Also, Polearm Master is arguably trying to translate the advantage that a polearm provides in the real world when fighting an opponent with much less reach - there's a significant distance they have to cover before getting in hitting range where you can hit them and they can't hit you back. If someone teleports next to you, they've avoided that dangerous situation whatever edge having that extra reach produced is lost.
Granted, that kind of reach advantage is also present with other weapons (e.g. a rapier vs a dagger) but D&D combat has to be streamlined, work in both 1v1 duels and group skirmishes, and polearms exploit that advantage to a greater degree than most other weapons in typical usage (pikes and halberds are extremely long.)
Anyways on the topic of reach and cover, this thread is super long so I might've missed something, but Jeremy Crawford did rule once that your reach does not extend into the wall or floor. And in my opinion that's the only sensible way to do it; I'm gonna be contrary here and say burrowing monsters aren't intended to get away scot-free. I don't care how good at burrowing the monster is, turning your back on an opponent to dig downwards is a bad idea and there's no way they can dig through solid ground faster than other enemies can jog away from you. You could sensibly make exceptions for special monsters like ghosts and earth elementals that don't dig so much as phase through things, but those are much rarer and already have special traits to account for their unique movement. Also there's not much of a point in declaring that your reach extends past a glass wall and an enemy beyond the wall provokes since you won't be able to target them with the attack anyways.
Anyways even if you rule that going around a corner into total cover counts as leaving reach and warrants an opportunity attack I don't think anyone's brought up that they should have 3/4 cover in that situation so I don't think it's a big deal either way. The same would be true if someone was going the other way into the reach of a player with Polearm Master: the OA would be provoked while most of them is still behind cover. So it really comes down to "no attack" vs "attack that's unlikely to hit", which doesn't seem worth debating to death to me. Go with whatever outcome you prefer.
This is probably the best compromise between the two sides. Neither side seems willing to concede the point and both sides have a reasonable argument for why the rule should react the way that it does.
Setting aside what the rules actually say, which I will agree is not entirely clear, it's worth considering what the rules should say. For that, we need to know what opportunity attacks are modeling.
In general, when you are in combat and facing your opponent, you have two defenses against being attacked:
You can defend against the attacks (block, dodge, parry, etc).
You can threaten your enemy (if the enemy tries to hit you, they open themselves up to you hitting them).
When someone with a short weapon is fighting someone with a longer weapon, there is a region where the person with the shorter weapon can be attacked, but cannot attack (i.e. defense (2) is unavailable), and it is somewhat difficult to get through safely (your ability to do (1) is also constrained by limitations on where you can move). That appears to be what PAM is trying to model, though it's doing it wrong (it should be something like: any time a foe is within your reach, but you are not within their reach, they provoke). If you have a way to pass through that zone without being attacked, you should be safe.
On the opposite side of things, if you want to retreat from (or run past) a foe, you either have to move while facing them (which is slow, and in the case of difficult terrain, hazardous), or you have to turn away (making both of your defenses less effective or even entirely nonexistent). The safe way to retreat is that you move away while facing until you can reach a location where you can safely turn. Since in the real world movement is simultaneous, this usually requires an obstacle of some sort. For a burrowing creature, if the creature is able to burrow while backing away, they should be safe, if the creature has to turn and dig, not safe. Most creatures in D&D that can burrow without leaving a hole behind seem to simply magically treat stone like water or air and thus should be able to retreat, but the rules don't actually make it clear.
If a PAM can get an OA against someone teleporting next to them why can't anyone else? It clearly doesn't make sense that a long weapon has that advantage over a shorter weapon. I side with the argument that a line has to be crossed. This fits with how the feat was intended to be used (keeping an enemy at bay with the threat of the weapon's reach). I also agree that it is an excellent way to slightly diminish an OP feat.
That's fine if you want to play it like that. Take it to the homebrew forum. This is the Rules and Mechanics Forum. RAW is important for the Rules and Mechanics Forum. Just because people argue for RAW doesn't mean that they always agree with RAW. Shield works exactly the way that you mentioned in your example RAW mechanically. The Narrative description will be different, but mechanically that's how it works. Mechanically, the polearm bro doesn't get an OA at 5 ft unless the bro is also a Cavalier or is using the UA Tunnel Fighter Fighting Style (which is the spiritual ancestor of Cavalier and won't see life in an official WotC book in that form).
Polearm Master: While you are wielding a glaive, halberd, pike, quarterstaff, or spear, other creatures provoke an opportunity attack from you when they enter the reach you have with that weapon.
Opportunity Attacks
In a fight, everyone is constantly watching for a chance to strike an enemy who is fleeing or passing by. Such a strike is called an opportunity attack.
You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.
You can avoid provoking an opportunity attack by taking the Disengage action. You also don't provoke an opportunity attack when you teleport or when someone or something moves you without using your movement, action, or reaction. For example, you don't provoke an opportunity attack if an explosion hurls you out of a foe's reach or if gravity causes you to fall past an enemy.
The general rule states that you must see the creature move out of your reach. PAM adds that you can make an OA (which requires that you see the creature) when they enter the reach that you have with that weapon. Whichever weapon you are using to make the PAM attack determines the reach, and you must still be able to see the creature to make the OA otherwise PAM would have told you differently since the general rule is that you must see the creature. Creatures that enter your reach that you don't see don't provoke OAs because you don't know that they are there until they are within your reach. (Does that necessarily make sense? Not always, but hey magic is cool, so let's keep that but forget this other stuff because it's not cool for my character). You get to attack the creature normally later. If you want to make the attack against a teleporting creature, use mage slayer to use your reaction to make an attack against the caster (not an OA by the way).
If the DM is adjudicating the game in a way that makes it unfun for you, have a discussion with them. If they decide that they agree with you, awesome. If they explain their position in a way that appeases you and you want to continue with the character, awesome. If they don't explain their position in a way that appeases you, ask if you can rework the character in a way that will fit the game that is being played, ask to make a new character, or find a DM that does agree with you.
That's not homebrew man, that's his interpretation of the Rules. And his interpretation belongs in this forum just as much as the people who like to argue RAW all the time.
This sub is called Rules and Mechanics, not Rules As Written. It's for discussing the rules of the game and sharing how you apply those rules... not telling people to get out because they don't think like you - that's what Facebook is for, and there's no need to bring that kind of cancerous and toxic shit in here.
...cryptographic randomness!
Thanks Urandom.
Sometimes I think people trying to interpret RAW forget that you can still use common sense. I feel like the rules were written with the underlying assumption that most people would use common sense and not take things in the most literal mechanical way so as to not require every little detail possible to be included in the description of every spell, ability, etc. If I have a crossbow that can shoot 80 ft but, I'm in a 20 ft room, obviously my range is now some fraction of that depending on where I am standing.It would be the same thing for a reach weapon that has it's reach obstructed. You have a max range and an effective range which is circumstantial. Okay, call that Homebrew, I'm sure you will.
Now for some more common sense. You can't AoO someone who teleports away because they simply aren't there anymore. If someone teleports to you, I would think that this scenario reversal doesn't play out the same way.
Common sense is useful for deciding what is RAI. It's not relevant to RAW -- RAW is strictly about textual analysis. Which does mean a lot of rules discussions don't have any final resolution because RAW is not clear.
Yes, that is actually a better way to capture what I mean, RAI is just an opinion though but, hopefully correctly determined with common sense.
The thing I find most amusing is no one calls this a rule exploit. Usually some power gamer comes up with a RAW argument that can't be disproved and unbalances the game unfairly to his advantage. I don't see this topic any differently except it happens at the expense of the player instead of to his benefit.
The reason for RAW is for balance. This is a game after all. If an DM wants to rule outside of RAW because that's what fits their game better, that's how it should be played. If a DM wants to follow RAW because that eases the burden that they have placed on them, then that's how it should be played.
Saying that a reach weapon can't take an OA at 5 ft is a balance issue that the developers placed in the game. Interpreting that you can't OA a creature that teleports in is a mechanical balance effect that follows RAW. If we think of an OA as something that just barely happens on the reaction (because of the fact that it happens just before the target leaves your reach, then it would make sense for the PAM user to be watching the approaching character and making the attack when they come in. If they can't see the character come in because of burrowing or teleporting, there would be a sense of surprise that they showed up particularly if the PAMist is watching other things happening and focusing on that.)
For that matter, why should the PAM player be the only one that gets the OA coming into each? Mechanics. Why should the PAM player get the bonus action and not the longsword player? Mechanics.
I'm not arguing the threatened areas, I'm arguing the reach or in the case of your crossbow example range. Your range doesn't become hampered permanently when you enter a room nor does your reach become 5 ft or 0 ft because you stand next to a wall. If those were the case, I'd see a reason for your OA to go off while the creature was still in your "Old" range. But it doesn't work like that.
My common sense says that popping up inside reach shouldn't draw an opportunity attack from PAM; it represents what seems to me a perfectly plausible situation. NightskyPirate I assume has the opposite opinion. Hence the problem with 'common sense'.
Threatened area is not a thing in 5e. And RAW, Reach itself is not defined, it merely says that most creatures have 5' reach.
When something enters reach is determined by the GM, that is not defined by RAW. I'm acknowledging you can be right by the fact that the rules doesn't define what Reach is, which I'm gonna say again, Reach does not reach through things.
That's actually the point that I've been arguing. That you are using this as an exploit that benefits the player because the rules don't say that you can do it that way. You're interpreting the rules one way. I'm interpreting the rules another way. By extension, everyone in this thread is doing the same thing.
It's clear to me that the way that I'm interpreting it is correct. You seem pretty adamant that your interpretation is correct. That means there is an impasse that won't be resolved until we're in a game together and the DM rules in favor of one side or the next. The following DM might be rule the other way or might be of the same opinion. SAC might even have clarification, but that won't change what is written (though I consider it carefully since I'm usually relying on the rules for structure and knowing the intent matters to me).
On the contrary, these debates only tend to go on when there is a tenuous, shaky RAW interpretation that someone very strongly believes in which contradicts common sense and RAI. I admit that the RAW is not 100% clear because the Reach term is used in two different ways - 1) to determine what you can hit, and 2) to determine a boundary that triggers OA's and other reactionary attacks such as the one from PM.
My homebrew subclasses (full list here)
(Artificer) Swordmage | Glasswright | (Barbarian) Path of the Savage Embrace
(Bard) College of Dance | (Fighter) Warlord | Cannoneer
(Monk) Way of the Elements | (Ranger) Blade Dancer
(Rogue) DaggerMaster | Inquisitor | (Sorcerer) Riftwalker | Spellfist
(Warlock) The Swarm
As scatterbraind said...
Only can end peacefully when both parties agree that RAW can be interpreted both ways... unless it can't.
Just want to reiterate one point:
Total Cover is equivalent to being behind a wall, if a creature behind a wall was standing next to me he is concealed by the wall which means
1) he does not provoke opportunity attack
"You can make an opportunity attack when a hostile creature that you can see moves out of your reach." - PHB Opportunity Attacks (Using DnD Beyond)
2) Even if not using PAM, if you wanted to target this creature with a melee attack, you would have to move into reach, which would mean moving around his total cover.
Your reach does not extend through solid/impassable objects, even if the target is within 5ft behind a solid wall you may not attack him through the wall.
Notice how when discussing melee attacks the word "reach" is used and not "range". This is to highlight the difference between being in range of someone (spell) and being in reach of someone (melee attack). The creature can be within range but not within reach.
This is further demonstrated in spell attacks:
Inflict Wounds:
Range/Area - Touch
"Make a melee spell attack against a creature you can reach."
VS.
Firebolt:
Range/Area: 120ft
"You hurl a mote of fire at a creature or object within range. Make a ranged spell attack against the target. On a hit, the target takes 1d10 fire damage."
Sidenote: If you're going to make the argument that this is grid combat, then please refer to
" was 5 feet away from the a corner and a creature came around the corner. " From the OP's post.
If the argument is made that being around the corner is full cover, then anything behind that corner is concealed and thus unable to be attacked/targeted and thus not inside your reach.
I don't believe that definitively says that full cover restricts reach. In other words, those that say reach does extend through full cover would not be wrong because of those cited rules.
I do believe it is the correct interpretation, of course... just saying I think the folks who want to stick by PAM not provoking should be able to say they aren't going against RAW. I believe RAW doesn't specifically back anyone up here. Though I really think reach does work in the way prescribed above by snowboon.
Right, the problem with "Reach"/"Range"/"Touch" is that there aren't any book definitions of these terms (Aside from Reach being a property of a weapon) so I was using context clues in the book to help define the term.
Because if you do a strictly RAW then you can't infer one way or the other that terrain blocks or does not block reach, but using context clues such as Inflict Wounds you can gather than you need to make contact with someone/something. Terrain such as a wall or door would obviously block contact and the spell wouldn't even fail as you wouldn't be able to cast it because you have no target. (Total Cover)
If you wanted to punch someone behind a wall you would have to punch the wall or move around the wall. The DM could also rule that you can punch through the wall and hit him, but that is purely flavor/DM discretion.
I mean if you wanna bring in world logic into this, someone teleporting right next to you would be extremely difficult to anticipate. Also, Polearm Master is arguably trying to translate the advantage that a polearm provides in the real world when fighting an opponent with much less reach - there's a significant distance they have to cover before getting in hitting range where you can hit them and they can't hit you back. If someone teleports next to you, they've avoided that dangerous situation and whatever edge having that extra reach produced is lost.
Granted, that kind of reach advantage is also present with other weapons (e.g. a rapier vs a dagger) but D&D combat has to be streamlined, work in both 1v1 duels and group skirmishes, and polearms exploit that advantage to a greater degree than most other weapons in typical usage (pikes and halberds are extremely long.)
Anyways on the topic of reach and cover, this thread is super long so I might've missed something, but Jeremy Crawford did rule once that your reach does not extend into the wall or floor. And in my opinion that's the only sensible way to do it; I'm gonna be contrary here and say burrowing monsters aren't intended to get away scot-free. I don't care how good at burrowing the monster is, turning your back on an opponent to dig downwards is a bad idea and there's no way they can dig through solid ground faster than other enemies can jog away from you. You could sensibly make exceptions for special monsters like ghosts and earth elementals that don't dig so much as phase through things, but those are much rarer and already have special traits to account for their unique movement. Also there's not much of a point in declaring that your reach extends past a glass wall and an enemy beyond the wall provokes since you won't be able to target them with the attack anyways.
Anyways even if you rule that going around a corner into total cover counts as leaving reach and warrants an opportunity attack I don't think anyone's brought up that they should have 3/4 cover in that situation so I don't think it's a big deal either way. The same would be true if someone was going the other way into the reach of a player with Polearm Master: the OA would be provoked while most of them is still behind cover. So it really comes down to "no attack" vs "attack that's unlikely to hit", which doesn't seem worth debating to death to me. Go with whatever outcome you prefer.
The Forum Infestation (TM)
This is probably the best compromise between the two sides. Neither side seems willing to concede the point and both sides have a reasonable argument for why the rule should react the way that it does.
Setting aside what the rules actually say, which I will agree is not entirely clear, it's worth considering what the rules should say. For that, we need to know what opportunity attacks are modeling.
In general, when you are in combat and facing your opponent, you have two defenses against being attacked:
When someone with a short weapon is fighting someone with a longer weapon, there is a region where the person with the shorter weapon can be attacked, but cannot attack (i.e. defense (2) is unavailable), and it is somewhat difficult to get through safely (your ability to do (1) is also constrained by limitations on where you can move). That appears to be what PAM is trying to model, though it's doing it wrong (it should be something like: any time a foe is within your reach, but you are not within their reach, they provoke). If you have a way to pass through that zone without being attacked, you should be safe.
On the opposite side of things, if you want to retreat from (or run past) a foe, you either have to move while facing them (which is slow, and in the case of difficult terrain, hazardous), or you have to turn away (making both of your defenses less effective or even entirely nonexistent). The safe way to retreat is that you move away while facing until you can reach a location where you can safely turn. Since in the real world movement is simultaneous, this usually requires an obstacle of some sort. For a burrowing creature, if the creature is able to burrow while backing away, they should be safe, if the creature has to turn and dig, not safe. Most creatures in D&D that can burrow without leaving a hole behind seem to simply magically treat stone like water or air and thus should be able to retreat, but the rules don't actually make it clear.
If a PAM can get an OA against someone teleporting next to them why can't anyone else? It clearly doesn't make sense that a long weapon has that advantage over a shorter weapon. I side with the argument that a line has to be crossed. This fits with how the feat was intended to be used (keeping an enemy at bay with the threat of the weapon's reach). I also agree that it is an excellent way to slightly diminish an OP feat.