It's an inevitable result of D&D's quite poor design, featuring such blunders as binary success and save or lose effects. Without leaving the system, the only alternative is arbitrarily high saving throws, spell resistance, or immunities, which are really all the same thing - your power fails to work, you waste your turn, and you don't get to have fun.
There is no way for a player to spend resources to overcome a foe's defenses, outside of niche, weak options like the lucky feat, that you have to specifically choose at character creation.
There are no ablative defenses. You can't reduce an enemy's AC or saves with attacks or powers, outside of, again, a handful of specific spells.
Combat stunts, when they exist at all, are a joke, and are only viable for those characters who invest an unreasonable amount of resources into being good at them, crippling their effectiveness at anything else.
The most useful spells in the game are those that remove one or more creatures from play instantly when successful, and do nothing if saved. This ensures that at least one person won't have fun when these spells are cast, and the system design incentivizes players and GMs to use only these spells, since almost anything else is a waste of an action.
There are systems that solve all of these problems.
There is a very simple way for, as you say, "...a player to spend resources to overcome a foe's defenses..." Just don't use save or suck spells. The majority of damage spells do half damage on a save, so whatever happens, you will still be doing significant damage. That is using spell slots to do damage regardless of defenses.
There is a very simple way for, as you say, "...a player to spend resources to overcome a foe's defenses..." Just don't use save or suck spells. The majority of damage spells do half damage on a save, so whatever happens, you will still be doing significant damage. That is using spell slots to do damage regardless of defenses.
People resist using damaging spells against bosses because spellcaster damage vs single targets is mostly terrible. To some degree that's probably by design, as it gives martial characters a distinctive 'boss slayer' role, but it does put this obligation on the DM to make sure that the high profile fights have a wide enough range of challenges to make everyone feel valuable (video games tend to solve this by having adds to boss fight that need to be controlled or blown up).
There is a very simple way for, as you say, "...a player to spend resources to overcome a foe's defenses..." Just don't use save or suck spells. The majority of damage spells do half damage on a save, so whatever happens, you will still be doing significant damage. That is using spell slots to do damage regardless of defenses.
People resist using damaging spells against bosses because spellcaster damage vs single targets is mostly terrible. To some degree that's probably by design, as it gives martial characters a distinctive 'boss slayer' role, but it does put this obligation on the DM to make sure that the high profile fights have a wide enough range of challenges to make everyone feel valuable (video games tend to solve this by having adds to boss fight that need to be controlled or blown up).
There is a very simple way for, as you say, "...a player to spend resources to overcome a foe's defenses..." Just don't use save or suck spells. The majority of damage spells do half damage on a save, so whatever happens, you will still be doing significant damage. That is using spell slots to do damage regardless of defenses.
People resist using damaging spells against bosses because spellcaster damage vs single targets is mostly terrible. To some degree that's probably by design, as it gives martial characters a distinctive 'boss slayer' role, but it does put this obligation on the DM to make sure that the high profile fights have a wide enough range of challenges to make everyone feel valuable (video games tend to solve this by having adds to boss fight that need to be controlled or blown up).
Guaranteed 100/12D12 damage is pretty powerful. Disintegrate is 106.5 average damage if upcasted to level 9, though admittedly it is all avoided with a save. There's also tsunami, and earthquake could be pretty devastating in a city.
Guaranteed 100/12D12 damage is pretty powerful. Disintegrate is 106.5 average damage if upcasted to level 9, though admittedly it is all avoided with a save. There's also tsunami, and earthquake could be pretty devastating in a city.
By the time you are tossing 9th level spells a martial is dishing out piles of damage every round and power word kill is only 78 damage if they aren't under 100, which lol why don't they just have it do 100 damage no save. Tsunami and earthquake are great spells, but not great single target damage. But hey if you want to wipe out an army those are good choices.
Guaranteed 100/12D12 damage is pretty powerful. Disintegrate is 106.5 average damage if upcasted to level 9, though admittedly it is all avoided with a save. There's also tsunami, and earthquake could be pretty devastating in a city.
By the time you are tossing 9th level spells a martial is dishing out piles of damage every round and power word kill is only 78 damage if they aren't under 100, which lol why don't they just have it do 100 damage no save. Tsunami and earthquake are great spells, but not great single target damage. But hey if you want to wipe out an army those are good choices.
By my (probably terrible) estimates, a martial will be doing less than 50 average dpr, not accounting for magic items, at level 20. 12D12 might not sound amazing, but that is automatic damage. Also, if you can get them off, tsunami and earthquake both do considerable damage and can force many saves.
power word kill is only 78 damage if they aren't under 100, which lol why don't they just have it do 100 damage no save
Because there are umpteen features and abilities in the game that trigger on going to 0 hp, which the wording on PWK circumvents
Rollback Post to RevisionRollBack
Active characters:
Carric Aquissar, elven wannabe artist in his deconstructionist period (Archfey warlock) Lan Kidogo, mapach archaeologist and treasure hunter (Knowledge cleric) Mardan Ferres, elven private investigator obsessed with that one unsolved murder (Assassin rogue) Xhekhetiel, halfling survivor of a Betrayer Gods cult (Runechild sorcerer/fighter)
By my (probably terrible) estimates, a martial will be doing less than 50 average dpr, not accounting for magic items, at level 20.
The idea that a level 20 doesn't have a magic weapon is kind of laughable. However, even without that
Berserker Barbarian, Level 20; Str 25, great weapon mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22
Attack 1: using improved brutal strike, attack bonus is +13, without advantage. 100% to hit (60% we hit without needing combat prowess), damage 2d6+7(str)+6(PB)+4(rage)+2d10(IBS)+4d6(frenzy) = 49. 5% chance we crit for another 32 (+1.6 damage). Oh, and we're applying status effects.
Attack 2: using reckless attack, hit chance would be 84%, but because we might have combat prowess left over, actual hit probability is 93.6%. Damage on a hit is 24, but miss chance drops that to 22.5. 9.75% chance we critical hit for another 7, for 23
Bonus Action: 14% chance Hew lets us make an attack. This attack doesn't add PB to damage and is only about 90% to hit, for another 2 damage.
Expected damage, no magic items: 75. Magic items can increase this substantially.
Champion Fighter, Level 20; Str 21, great weapon fighting and mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22 (50% to hit)
When making 4 attacks, normally we would only hit with two. However, boon of combat prowess will turn the first miss into a hit, and heroic warrior has a 50% chance to turn the second hit, and if we manage to miss studied attacks comes into play, so expected hits per attack action is about 3.5, including 0.6 critical hits. If we're using a maul and the crusher feat . Each hit does 2d6(w/GWM)+11 (19) (66.5 dpr), critical hits add another 4.8 damage. We also have a 48% chance to get an extra attack from Hew (which might trigger crusher or slasher, if we took those feats) for another 3.2 dpr, total 74.5 dpr. Oh, and action surge exists and we can use it 2x per short rest.
And all that is with no magic items and an AC 22 target. With realistic weapons it's trivially possible to exceed 100 dpr.
By my (probably terrible) estimates, a martial will be doing less than 50 average dpr, not accounting for magic items, at level 20.
The idea that a level 20 doesn't have a magic weapon is kind of laughable. However, even without that
Berserker Barbarian, Level 20; Str 25, great weapon mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22
Attack 1: using improved brutal strike, attack bonus is +13, without advantage. 100% to hit (60% we hit without needing combat prowess), damage 2d6+7(str)+6(PB)+4(rage)+2d10(IBS)+4d6(frenzy) = 49. 5% chance we crit for another 32 (+1.6 damage). Oh, and we're applying status effects.
Attack 2: using reckless attack, hit chance would be 84%, but because we might have combat prowess left over, actual hit probability is 93.6%. Damage on a hit is 24, but miss chance drops that to 22.5. 9.75% chance we critical hit for another 7, for 23
Bonus Action: 14% chance Hew lets us make an attack. This attack doesn't add PB to damage and is only about 90% to hit, for another 2 damage.
Expected damage, no magic items: 75. Magic items can increase this substantially.
Champion Fighter, Level 20; Str 21, great weapon fighting and mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22 (50% to hit)
When making 4 attacks, normally we would only hit with two. However, boon of combat prowess will turn the first miss into a hit, and heroic warrior has a 50% chance to turn the second hit, and if we manage to miss studied attacks comes into play, so expected hits per attack action is about 3.5, including 0.6 critical hits. If we're using a maul and the crusher feat . Each hit does 2d6(w/GWM)+11 (19) (66.5 dpr), critical hits add another 4.8 damage. We also have a 48% chance to get an extra attack from Hew (which might trigger crusher or slasher, if we took those feats) for another 3.2 dpr, total 74.5 dpr. Oh, and action surge exists and we can use it 2x per short rest.
And all that is with no magic items and an AC 22 target. With realistic weapons it's trivially possible to exceed 100 dpr.
Adding to this a level 20 devotion paladin can get a 20 in strength, 20 charisma, great weapon master, and the boon of combat prowess. This gives them a +16 to hit when using their sacred weapon. If you use divine smite when you use combat prowess or crit on the first attack or when you hit on the second attack you guarantee that you will divine smite and hit at least once. If you follow that set up, you have a 94% chance to hit twice on a turn and always uses divine smite even if you only hit once. This doesn't add weapon masteries or factor in undead and fiends with divine smite. Against that same 22 AC your DPR using 4th level smites is 71.43, 5th level is 76.31. You would have 2 turns of the 5th level DPR and 3 turns of the 4th level DPR. Math shown below.
By my (probably terrible) estimates, a martial will be doing less than 50 average dpr, not accounting for magic items, at level 20.
The idea that a level 20 doesn't have a magic weapon is kind of laughable. However, even without that
Berserker Barbarian, Level 20; Str 25, great weapon mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22
Attack 1: using improved brutal strike, attack bonus is +13, without advantage. 100% to hit (60% we hit without needing combat prowess), damage 2d6+7(str)+6(PB)+4(rage)+2d10(IBS)+4d6(frenzy) = 49. 5% chance we crit for another 32 (+1.6 damage). Oh, and we're applying status effects.
Attack 2: using reckless attack, hit chance would be 84%, but because we might have combat prowess left over, actual hit probability is 93.6%. Damage on a hit is 24, but miss chance drops that to 22.5. 9.75% chance we critical hit for another 7, for 23
Bonus Action: 14% chance Hew lets us make an attack. This attack doesn't add PB to damage and is only about 90% to hit, for another 2 damage.
Expected damage, no magic items: 75. Magic items can increase this substantially.
Champion Fighter, Level 20; Str 21, great weapon fighting and mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22 (50% to hit)
When making 4 attacks, normally we would only hit with two. However, boon of combat prowess will turn the first miss into a hit, and heroic warrior has a 50% chance to turn the second hit, and if we manage to miss studied attacks comes into play, so expected hits per attack action is about 3.5, including 0.6 critical hits. If we're using a maul and the crusher feat . Each hit does 2d6(w/GWM)+11 (19) (66.5 dpr), critical hits add another 4.8 damage. We also have a 48% chance to get an extra attack from Hew (which might trigger crusher or slasher, if we took those feats) for another 3.2 dpr, total 74.5 dpr. Oh, and action surge exists and we can use it 2x per short rest.
And all that is with no magic items and an AC 22 target. With realistic weapons it's trivially possible to exceed 100 dpr.
How in the world does the barbarian have a 49.5% chance to crit?
How in the world does the barbarian have a 49.5% chance to crit?
Sorry, that's just bad layout. 49 damage, 5% chance to crit.
Got it. Well, I did say my estimate was probably terrible.
I think most martials can hit about 50 DPR without magic items and some minimal optimization. A non gish spellcaster will probably struggle to keep with single target DPR of martials. Single target DPR is not usually the role of a spellcaster. The problem that OP is bringing up isn't really about legendary resistance but that when a monster makes a save against control spells nothing happens. Legendary resistance only makes that scenario guaranteed to happen if you use control effects on them. If people don't have different strategies for enemies resistant to control effects then that's poor planning. If anything lower tier monsters should have a weaker form of legendary resistance to encourage players to develop different strategies.
Legendary Effects, like auto-save, have been play-tested since the turn of the millennium. They are the best way for an Epic fight not to be over in 1 sec.
First guy up casts Hold Person, Dominate, Friends or any control spell. a failure by the Epic BBEG and the whole dungeon is over, as the sneaky guy goes over and slits his throat while the rest of the party engage the minions. Or better yet, Dominate and have the BBEG ORDER his minions t help carry out the loot, as you behead them as they carry their last chest to the surface! Although the first time this is done it is unique, fun and kind of cool. After the first time it make s the dungeon suck and kind of a let down.
Being able to not fail the first save is an important feature. You could just give them the ability to have MAD Save stats, but that becomes a huge game of how much? and if the GM is having a above average night, no spell will work. Legendary saves however are limited, and eventually a failed save will work, just no in the first round or two. Frankly, I am very sus that this joker says he is a GM. What Master makes an entire challenging dungeon and wants to let his climactic epic battle with the BBEG be over in 1 second? I highly doubt his unverified/claimed credentials.
On the player side, have one or two PCs casting low level save or suck spells until the BBEG runs out of legendary saves, then start casting the nasty spells. There are also spells you can start casting like Bane, Silvery Barbs, Curse or Contagion to give BBEG disadvantage. Or if there is a Sorcerer/Sorlock/Soradin in the party, once out of Legendary, they start casting everything with heightened ability on it to give auto-disadvantage to saves.
Legendary Actions and Resistances are there to balance the action economy and counter four to six characters focusing all their abilities onto a single target, as happens in every "boss" style fight. Even with minions, the group is likely to focus on the boss first, and whenever they can. They are needed because of the way 5e failed to balance the game, previous editions did just fine without them, but were balanced differently.
Yes, it does suck being the only spellcaster in the group, especially if your spells are of the control-type meant to inflict statuses as opposed to doing raw damage. Especially since most fights in 5e24 only last 3-4 rounds, which means against a single caster of that type, the Boss will never fail a save. This wasn't a problem in 5e14, because fights there tended to run closer to 10 rounds. It meant you could burn thru the legendary resistances and still have an effect later in the fight. But 5e24 fed every class and subclass (with only 1 or 2 exceptions) muscle milk. They also increased some of the damage of the monsters, but failed to increase the character or monster hp. Now fights rarely go past 3-4 rounds (yet take longer to resolve those 3-4 rounds than the 10 rounds fights did in 5e14 becaues now everyone has more things they can do each round), because the characters can dish out IMHO way too much damage.
Both sides are right. Legendary Resistances and Actions are now necessary, but they are necessary because of the game being out of balance. Legendary Resistances and Actions are ways for the DM to place their thumb on the scale to tilt things back to where they should have been. It is a poorly designed system, that had to build in a 'cheat' to compensate.
Our groups tends to prefer open rolls, because at various times we had DMs that fudged rolls so heavily that it felt more like characters vs DM than cooperative storytelling. There's one DM in particular that no player playing a spellcaster would ever take a spell that offered a save or no effect because the DM's monsters and NPCs would NEVER fail a save. So to rebuild trust in the group, I started rolling everything in the open. A good DM doesn't need to fudge die rolls to create a good story.
I have been on both sides of this issue. I have used Legendary Resistances and watched as player's face extreme disappointment because their ONE shot was summarily dismissed, not by skill, not by chance, but by fiat (Legendary Resistance). I have also been that player. I have a character now that used mostly control-type spells, and the other 2 spellcasters only use damage spells. It means my character almost never gets to see the big baddie affected by one of my spells, because they use all of their resistances vs spells from my character (or the fight would be over). There aren't always minions to use spells on, and let's face it, most minions are minions because they are nowhere near the threat level of the big baddie. Hypnotizing a couple of goblins doesn't carry with it the same fun as hypnotizing the giant that's dropping PCs in a single round (just an example).
So, both sides are right. It is necessary, but only because 5e24 is horribly out of whack. And to the person who said they have never seen a boss 'one-shotted', it may not be a one-shot, but i've seen groups (under 10th level) drop 600 hp monsters before the monster even gets warmed up. One DM I currently play under, gives every monster max hp x 4, because of how much damage our 6th level group can do (and technically, there's only 1 min/maxer in the group of six).
Legendary Actions and Legendary Resistances are a bandaid that has become permanent because of poor balance. In previous versions of the game characters could go as high as 100th level, back around 2nd or 3rd edition this was lowered and the predecessor to the current Legendary Actions/Resistances was used only for monsters that 20th+ level characters would be facing.
Rollback Post to RevisionRollBack
Playing D&D since 1982
Have played every version of the game since Basic (Red Box Set), except that abomination sometimes called 4e.
Pretty much what harmassassin said. Effectively since 3es save system came into play some kind of fix was needed. I have not played pathfinder2e, but they have a fix in which included nerfing spells, and buffing saves, with stagered levels of success/failure no idea if that plays out better than this. I'm sure it works, but from just reading it without actual play experience, in boss fights it looked like spellcasters just did mild distractions so the hero's of the story could kill the monster, or if their class permitted buffed the party. Which to be fair is no worse than a spellcaster insta shutting down entire fights. Or 3 rounds of legendary resistance and then the fight is over. Back in 2e and before it was closer to pathfinder 2es system where bosses just had good enough saves they basically never failed. Or more accurately the fail rate was low enough the spellcaster chose other options like save for 1/2 damage spells or buffing the party.
Legendary Resistance is needed in 5e because 5e did a terrible job balancing status effects (status effects are things all games have difficulty with, but 5e is worse even than other editions of D&D).
If we look at the simplest case of incapacitating status effects, it should be evident that the value of an incapacitate is equal to the value of the actions that are prevented; preventing a giant from taking an action is just more useful than preventing a kobold from taking an action. You can balance this by making the incapacitate less effective or reliable on the more powerful creature -- for example, if we expect a level 1 spell to prevent 10 damage, it should last 3 rounds on a kobold that averages 3.5 damage per round, half a round on a giant that averages 20 damage per round. In previous editions, defense against status effects scaled pretty strongly with monster HD/CR/Level, so the higher value of a status effect on a powerful monster was somewhat mitigated by a low chance of actually working (this doesn't mean it was zero problem.. but less of a problem than 5e), but 5e came up with the concept of 'bounded accuracy', and that means you have a fair number of high CR creatures with very poor status resistance.
There are other solutions than DC scaling (for example, hit point tests), but they have their own issues.
Legendary Resistance is needed in 5e because 5e did a terrible job balancing status effects (status effects are things all games have difficulty with, but 5e is worse even than other editions of D&D).
1e's status effects were generally "single save, lasts for duration". Those are much worse balanced than 5e's, which usually allow you to re-save each round. If you get a hold monster off on a dragon in 1e, the fight's over. In 5e, it's really quite bad for the dragon, but it's not necessarily an instant win.
And, much as you want to take down your main enemy right off the bat in a tactical sense, it's not fun. It turns fights into a coinflip. While legendary resists aren't great, they at least provide a defensive resource that you can burn through over the course of a fight. The dragon may get held, but there's gonna be some pyrotechnics first.
Fundamentally, save or suck effects are impossible to balance. The basic saving-throw mechanic means you either wasted your turn, or the monster is out the fight. If the penalty for a failed sale were less, then it's not worth trying. If there's still a meaningful effect on a successful save, they're likely too good. Ultimately the best way to balance them would be to rewrite the spells entirely, so that there's always some effect, but you can never take somebody out of the fight on a single roll, but that means getting rid of a bunch of classic spells. (And possibly the extra rule complication of stacking impairment effects.)
Rollback Post to RevisionRollBack
To post a comment, please login or register a new account.
There is a very simple way for, as you say, "...a player to spend resources to overcome a foe's defenses..." Just don't use save or suck spells. The majority of damage spells do half damage on a save, so whatever happens, you will still be doing significant damage. That is using spell slots to do damage regardless of defenses.
People resist using damaging spells against bosses because spellcaster damage vs single targets is mostly terrible. To some degree that's probably by design, as it gives martial characters a distinctive 'boss slayer' role, but it does put this obligation on the DM to make sure that the high profile fights have a wide enough range of challenges to make everyone feel valuable (video games tend to solve this by having adds to boss fight that need to be controlled or blown up).
Power Word Kill, Meteor Swarm, Prismatic Spray, Disintegrate, and so on. There are also buff spells, and combat spells that don't require a save.
Outside of meteor swarm you are basically just agreeing with him.
Guaranteed 100/12D12 damage is pretty powerful. Disintegrate is 106.5 average damage if upcasted to level 9, though admittedly it is all avoided with a save. There's also tsunami, and earthquake could be pretty devastating in a city.
By the time you are tossing 9th level spells a martial is dishing out piles of damage every round and power word kill is only 78 damage if they aren't under 100, which lol why don't they just have it do 100 damage no save. Tsunami and earthquake are great spells, but not great single target damage. But hey if you want to wipe out an army those are good choices.
By my (probably terrible) estimates, a martial will be doing less than 50 average dpr, not accounting for magic items, at level 20. 12D12 might not sound amazing, but that is automatic damage. Also, if you can get them off, tsunami and earthquake both do considerable damage and can force many saves.
Because there are umpteen features and abilities in the game that trigger on going to 0 hp, which the wording on PWK circumvents
Active characters:
Carric Aquissar, elven wannabe artist in his deconstructionist period (Archfey warlock)
Lan Kidogo, mapach archaeologist and treasure hunter (Knowledge cleric)
Mardan Ferres, elven private investigator obsessed with that one unsolved murder (Assassin rogue)
Xhekhetiel, halfling survivor of a Betrayer Gods cult (Runechild sorcerer/fighter)
The idea that a level 20 doesn't have a magic weapon is kind of laughable. However, even without that
Berserker Barbarian, Level 20; Str 25, great weapon mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22
Champion Fighter, Level 20; Str 21, great weapon fighting and mastery, boon of combat prowess, other features irrelevant. Target assumed AC 22 (50% to hit)
And all that is with no magic items and an AC 22 target. With realistic weapons it's trivially possible to exceed 100 dpr.
Adding to this a level 20 devotion paladin can get a 20 in strength, 20 charisma, great weapon master, and the boon of combat prowess. This gives them a +16 to hit when using their sacred weapon. If you use divine smite when you use combat prowess or crit on the first attack or when you hit on the second attack you guarantee that you will divine smite and hit at least once. If you follow that set up, you have a 94% chance to hit twice on a turn and always uses divine smite even if you only hit once. This doesn't add weapon masteries or factor in undead and fiends with divine smite. Against that same 22 AC your DPR using 4th level smites is 71.43, 5th level is 76.31. You would have 2 turns of the 5th level DPR and 3 turns of the 4th level DPR. Math shown below.
Attack 1: 33.8(5th), 32.23(4th)
Attack 2 with hit and no crit or combat prowess on attack 1 70% chance: 36.74(5th), 33.43(4th)
Attack 2 with combat prowess on 1st hit 25% chance: 4.56
Attack 2 with Crit on 1st hit 5% chance: 1.21
How in the world does the barbarian have a 49.5% chance to crit?
Sorry, that's just bad layout. 49 damage, 5% chance to crit.
Got it. Well, I did say my estimate was probably terrible.
I think most martials can hit about 50 DPR without magic items and some minimal optimization. A non gish spellcaster will probably struggle to keep with single target DPR of martials. Single target DPR is not usually the role of a spellcaster. The problem that OP is bringing up isn't really about legendary resistance but that when a monster makes a save against control spells nothing happens. Legendary resistance only makes that scenario guaranteed to happen if you use control effects on them. If people don't have different strategies for enemies resistant to control effects then that's poor planning. If anything lower tier monsters should have a weaker form of legendary resistance to encourage players to develop different strategies.
Legendary Effects, like auto-save, have been play-tested since the turn of the millennium. They are the best way for an Epic fight not to be over in 1 sec.
First guy up casts Hold Person, Dominate, Friends or any control spell. a failure by the Epic BBEG and the whole dungeon is over, as the sneaky guy goes over and slits his throat while the rest of the party engage the minions. Or better yet, Dominate and have the BBEG ORDER his minions t help carry out the loot, as you behead them as they carry their last chest to the surface! Although the first time this is done it is unique, fun and kind of cool. After the first time it make s the dungeon suck and kind of a let down.
Being able to not fail the first save is an important feature. You could just give them the ability to have MAD Save stats, but that becomes a huge game of how much? and if the GM is having a above average night, no spell will work. Legendary saves however are limited, and eventually a failed save will work, just no in the first round or two. Frankly, I am very sus that this joker says he is a GM. What Master makes an entire challenging dungeon and wants to let his climactic epic battle with the BBEG be over in 1 second? I highly doubt his unverified/claimed credentials.
On the player side, have one or two PCs casting low level save or suck spells until the BBEG runs out of legendary saves, then start casting the nasty spells. There are also spells you can start casting like Bane, Silvery Barbs, Curse or Contagion to give BBEG disadvantage. Or if there is a Sorcerer/Sorlock/Soradin in the party, once out of Legendary, they start casting everything with heightened ability on it to give auto-disadvantage to saves.
Both sides in this are right.
Legendary Actions and Resistances are there to balance the action economy and counter four to six characters focusing all their abilities onto a single target, as happens in every "boss" style fight. Even with minions, the group is likely to focus on the boss first, and whenever they can. They are needed because of the way 5e failed to balance the game, previous editions did just fine without them, but were balanced differently.
Yes, it does suck being the only spellcaster in the group, especially if your spells are of the control-type meant to inflict statuses as opposed to doing raw damage. Especially since most fights in 5e24 only last 3-4 rounds, which means against a single caster of that type, the Boss will never fail a save. This wasn't a problem in 5e14, because fights there tended to run closer to 10 rounds. It meant you could burn thru the legendary resistances and still have an effect later in the fight. But 5e24 fed every class and subclass (with only 1 or 2 exceptions) muscle milk. They also increased some of the damage of the monsters, but failed to increase the character or monster hp. Now fights rarely go past 3-4 rounds (yet take longer to resolve those 3-4 rounds than the 10 rounds fights did in 5e14 becaues now everyone has more things they can do each round), because the characters can dish out IMHO way too much damage.
Both sides are right. Legendary Resistances and Actions are now necessary, but they are necessary because of the game being out of balance. Legendary Resistances and Actions are ways for the DM to place their thumb on the scale to tilt things back to where they should have been. It is a poorly designed system, that had to build in a 'cheat' to compensate.
Our groups tends to prefer open rolls, because at various times we had DMs that fudged rolls so heavily that it felt more like characters vs DM than cooperative storytelling. There's one DM in particular that no player playing a spellcaster would ever take a spell that offered a save or no effect because the DM's monsters and NPCs would NEVER fail a save. So to rebuild trust in the group, I started rolling everything in the open. A good DM doesn't need to fudge die rolls to create a good story.
I have been on both sides of this issue. I have used Legendary Resistances and watched as player's face extreme disappointment because their ONE shot was summarily dismissed, not by skill, not by chance, but by fiat (Legendary Resistance). I have also been that player. I have a character now that used mostly control-type spells, and the other 2 spellcasters only use damage spells. It means my character almost never gets to see the big baddie affected by one of my spells, because they use all of their resistances vs spells from my character (or the fight would be over). There aren't always minions to use spells on, and let's face it, most minions are minions because they are nowhere near the threat level of the big baddie. Hypnotizing a couple of goblins doesn't carry with it the same fun as hypnotizing the giant that's dropping PCs in a single round (just an example).
So, both sides are right. It is necessary, but only because 5e24 is horribly out of whack. And to the person who said they have never seen a boss 'one-shotted', it may not be a one-shot, but i've seen groups (under 10th level) drop 600 hp monsters before the monster even gets warmed up. One DM I currently play under, gives every monster max hp x 4, because of how much damage our 6th level group can do (and technically, there's only 1 min/maxer in the group of six).
Legendary Actions and Legendary Resistances are a bandaid that has become permanent because of poor balance. In previous versions of the game characters could go as high as 100th level, back around 2nd or 3rd edition this was lowered and the predecessor to the current Legendary Actions/Resistances was used only for monsters that 20th+ level characters would be facing.
Playing D&D since 1982
Have played every version of the game since Basic (Red Box Set), except that abomination sometimes called 4e.
Pretty much what harmassassin said. Effectively since 3es save system came into play some kind of fix was needed. I have not played pathfinder2e, but they have a fix in which included nerfing spells, and buffing saves, with stagered levels of success/failure no idea if that plays out better than this. I'm sure it works, but from just reading it without actual play experience, in boss fights it looked like spellcasters just did mild distractions so the hero's of the story could kill the monster, or if their class permitted buffed the party. Which to be fair is no worse than a spellcaster insta shutting down entire fights. Or 3 rounds of legendary resistance and then the fight is over. Back in 2e and before it was closer to pathfinder 2es system where bosses just had good enough saves they basically never failed. Or more accurately the fail rate was low enough the spellcaster chose other options like save for 1/2 damage spells or buffing the party.
Boss fights are for video games.
Legendary Resistance is needed in 5e because 5e did a terrible job balancing status effects (status effects are things all games have difficulty with, but 5e is worse even than other editions of D&D).
If we look at the simplest case of incapacitating status effects, it should be evident that the value of an incapacitate is equal to the value of the actions that are prevented; preventing a giant from taking an action is just more useful than preventing a kobold from taking an action. You can balance this by making the incapacitate less effective or reliable on the more powerful creature -- for example, if we expect a level 1 spell to prevent 10 damage, it should last 3 rounds on a kobold that averages 3.5 damage per round, half a round on a giant that averages 20 damage per round. In previous editions, defense against status effects scaled pretty strongly with monster HD/CR/Level, so the higher value of a status effect on a powerful monster was somewhat mitigated by a low chance of actually working (this doesn't mean it was zero problem.. but less of a problem than 5e), but 5e came up with the concept of 'bounded accuracy', and that means you have a fair number of high CR creatures with very poor status resistance.
There are other solutions than DC scaling (for example, hit point tests), but they have their own issues.
1e's status effects were generally "single save, lasts for duration". Those are much worse balanced than 5e's, which usually allow you to re-save each round. If you get a hold monster off on a dragon in 1e, the fight's over. In 5e, it's really quite bad for the dragon, but it's not necessarily an instant win.
And, much as you want to take down your main enemy right off the bat in a tactical sense, it's not fun. It turns fights into a coinflip. While legendary resists aren't great, they at least provide a defensive resource that you can burn through over the course of a fight. The dragon may get held, but there's gonna be some pyrotechnics first.
Fundamentally, save or suck effects are impossible to balance. The basic saving-throw mechanic means you either wasted your turn, or the monster is out the fight. If the penalty for a failed sale were less, then it's not worth trying. If there's still a meaningful effect on a successful save, they're likely too good. Ultimately the best way to balance them would be to rewrite the spells entirely, so that there's always some effect, but you can never take somebody out of the fight on a single roll, but that means getting rid of a bunch of classic spells. (And possibly the extra rule complication of stacking impairment effects.)