I could use some tips on how to play a Gloom Stalker Tank.  I've found very few resources on how to play and build a Ranger Tank.

I've got 20 AC at level 3 with the Medium Armor Master Feat (taken at level 1 as a Variant Human), the Defense Fighting Style, Scale Mail, and a Shield.  Add on disadvantage when we're in darkness and fighting enemies that rely on darkvision, and I'm extremely difficult to hit.  Disadvantage also drops the enemy crit chance from 5% to 0.25%, which is a huge huge reduction.  20 AC is still pretty good when we're not in darkness.

But the obvious question is - how do I convince enemies to attack me?  A tank is no good if the enemies ignore him.  And if I am invisible, I am quite easy to ignore.

My plan is to multi-class into Arcane Trickster Rogue to pick up expertise in Stealth and Perception, Sneak Attack, the Booming Blade Cantrip, and the Shield Spell.  If I'm attacking with Booming Blade (and adding Sneak attack damage on top of it), that should get the enemy's attention, right?  What else can I do to try to goad enemies into attacking me? Maybe tell the DM that I am going to verbally taunt the guy next to me on his turn, and to see if he lets me do that without using an action?  I'll get War Caster one level after getting Booming Blade, so I can do a Booming Blade opportunity attack, that should at least make it painful for enemies to run away from me.

After I get both Ranger and Rogue to level 4, is it more important to get to level 7 in Ranger for Iron Mind, or to level 7 in Rogue for Uncanny Dodge and Evasion? 

I can't figure out what level 1 Enchantment and Illusion spells I would want as an Arcane Trickster.  We'll be at level 6 by the time I get these spells, and I only have a 10 in intelligence (we rolled for stats, and I rolled slightly worse than the standard array).  Any thoughts?

What techniques or strategies should I use in battle?  The party is currently a fairly tanky Wood Elf Kensei Monk, a Half Elf Hexblade Archer, a High Elf Evocation Wizard, and a Goblin Battlemaster Fighter-Archer, so we're a mostly ranged group, all with dark vision (and none with any healing spells except for me).

Edit: Summary

1) How do I get enemies to attack me?

2) After i get Ranger and Rogue to level 4, which class do I take out to level 8?

3) What spells should I take as an Arcane Trickster for Enchantment and Illusion?

4) What strategies and techniques should i use for controlling the battlefield a bit?

That is a lot of questions.  In the future, please consider numbering your questions so that responding clearly becomes easier.  

To be an effective tank, you probably want to use a combination of terrain, spells, and feats to make your PC as "sticky" as possible.  Sentinel would therefore be a good feat for you.  However, this would interfere with your plan to take Warcaster.

If you're going to take that many levels in Rogue, you might as well keep going in Rogue.  Given how important getting a 2nd attack is to a Ranger, you probably should delay multi-classing at least until you get to 5th level of Ranger.  So are you still sure you want to go for Arcane Trickster?   

I have edited the original post to add four numbered questions at the bottom. Thanks for that tip.

I know that multi-attack is usually a key Ranger ability, but I am trying to replace it with Booming Blade + Sneak Attack. So getting to level 5 in Ranger isn't that important to me. Did I judge this incorrectly?

I think the monk is planning to take Sentinel, and I think Sentinel kind of works against Booming Blade, so I don't plan on taking the feat.  Getting war caster to do the Booming Blade opportunity attacks should be a good way to really punish someone for running away from me. Sentinel would stop them from taking another 2D8 in thunder damage for voluntarily moving.

I am definitely considering going to level 8 Rogue after I get both classes to level 4. The proficiency in Wisdom saves for going Ranger to 8 does appeal to me, but it sounds like you think it's better to go with Rogue to 8 instead of Ranger to 8. Uncanny Dodge and Evasion do appeal to me. As does the Shadow Blade spell at level 7 Rogue (advantage helps guarantee that you hit and get the sneak attack damage almost every round).

I suggest Sentintel > Booming Blade b/c while BB adds a bit more damage, 2d8 averages out to only 5 points.  Not negligible, but what you really want to do is prevent them from running away from you after you've engaged them, right?  The purpose of a tank is to get your enemies to attack you rather than someone else.  BB punishes them, but a lot of higher tier enemies will just eat the 2d8 damage if it means the opportunity to go straight for the party Wizard.  Also, part of the purpose of having more attacks is that you get more opportunities to land a successful sneak attack.  You only get 1 per round, but you won't always land sneak attack without advantage.  In that sense, it makes as much if not more sense to get to 5th level of Ranger and then take Inquisitive or Swashbuckler for your subclass instead of ATrickster.  

First off, there's a very important clarification: Very often I get two Sneak attack damage per round, not one.  I get one sneak attack on my turn, and one sneak attack when I use my reaction to do an opportunity attack on somebody else's turn.


The war caster feat also gives advantage on concentration checks, which as a tank, should be fairly frequent.  And it allows me to cast spells with somatic components while holding both a shield and a weapon. Primarily important to me because of the Shield spell.  If I don't take war caster, I'll be much less inclined to cast concentration spells like Hunter's Mark (or Shadow Blade later on), and I won't be able to cast Shield as a reaction.  So if I don't take war caster, what spells should I be planning to use my 1st level spell slots for?  I was planning on pretty much only using those spell slots for Hunter's Mark and Shield.  The Booming Blade opportunity attack is my favorite part about war caster, but those other two bonuses are also very very important to me.

But now for my thoughts on Booming Blade vs Extra Attack, and why I chose Booming Blade (some calculations on damage):

Booming Blade is an extra 2D8 if they move, but it's also 2D8+3 (my Dex modifier) when I do the attack (from levels 5 to 10), plus the sneak attack damage.  So if they move, it's 4D8+3 damage+XD6 Sneak attack damage (where X is the number of dice I get for sneak attack).  And I get to do that on my turn and on my reaction. If I do Extra Attack + Sentinel, I get to do a pair of 1D8+3 damage attacks, with two chances to land the attack and get XD6 sneak attack damage.  And for my reaction, it's just 1D8+3+XD6 sneak attack damage.

So the higher tier enemies that will just eat the damage and run away would suffer 8D8+6 damage + 2XD6 Sneak attack damage from two attacks if I take war caster and Booming Blade, or 3D8+9 damage +2XD6 Sneak attack damage from three attacks if I take sentinel and extra attack (but with a slightly improved chance to land half of the sneak attack damage).  But they would have their movement speed cut to zero in the second situation.  I don't think that cutting their speed to zero is worth doing 5D8 less damage and not having the other benefits of war caster either.

Once I reach level 11 (the campaign is expected to end with us around level 14), I could have the Shadow Blade Spell if I go with Ranger 4 Rogue 7.  But without war caster, it would be a lot harder to maintain concentration on this spell.  Also, at level 11, the Booming Blade cantrip adds both an extra D8 on the initial damage and an extra D8 on the damage they take for moving.  Without adding in Shadow Blade, the above calculation improves to 12D8+6 damage +8D6 Sneak attack damage (assuming level 7 Rogue) for Booming Blade compared to 3D8+9+8D6 Sneak attack damage without Booming Blade.  Now its a 9D8 damage difference instead of 5D8 damage difference.

Adding in Shadow Blade for both would be 14D8+6 damage + 8D6 Sneak attack damage compared to 6D8+9+8D6 Sneak attack (down to "only" an 8D8 difference now).  But, with advantage on saving throws to maintain concentration on Shadow Blade for if I take war caster, and without advantage on saving throws to maintain concentration on Shadow Blade if I took sentinel instead.  And with the ability to cast the Shield spell as a reaction if I take war caster (helps for maintaining concentration), but without the ability to cast the Shield spell as a reaction if I took sentinel instead. So I would be much more likely to lose concentration on Shadow Blade if I went with sentinel + extra attack instead of war caster + booming blade.

If I'm not able to get Sneak attack damage, just remove the sneak attack damage portion from the calculations above, and the damage becomes very tilted in favor of War Caster + Booming Blade.  

If they don't move, and don't take damage from the 2nd part of Booming Blade, and I don't get an opportunity attack, the damage is slightly in favor of Extra Attack.  But the Sentinel feat is now not being used at all, while the war caster feat allowing me to cast shield as a reaction and having advantage on saving throws to make a concentration check is probably going to be relevant.

This is the same DM that did the campaign where I played an Arcane Trickster, so I'm anticipating opportunity attacks being quite plentiful because they were quite plentiful in the previous campaign that he was a DM for, and I don't expect his style of controlling enemies to have changed (especially since that campaign only ended last month).


And now for an explanation on why I choose Gloomstalker and why I plan to choose Arcane Trickster:

I'm not going Gloom Stalker Ranger because I want Extra Attacks.  I'm going Gloom Stalker Ranger because I want some levels with a D10 hit dice, because I want proficiency with shields, because I want the Defense Fighting Style, because I want the initiative boost and the extra movement speed on the first round (a tank without good mobility and without good initiative will have a harder time using positioning to help control the battlefield), because I want advantage on almost all attacks when I'm in total darkness (helps guarantee Sneak attack, and helps my chance to hit greatly), and because I want enemies to have disadvantage on their attacks on me when I'm in total darkness. And because it lets me play a human, but still pick up dark vision.

Having played an Arcane Trickster before, and having enjoyed it, I know how important getting that sneak attack damage is, and that's why I saw the Gloomstalker level 3 ability as a great way to get sneak attack fairly reliably.  I also know how important getting that second sneak attack each round from your opportunity attack is.  That second sneak attack each round is when my character really did a ton of damage in fights. And I know how important dark vision is when you're a Rogue.

I could see taking the Sentinel feat after I get War Caster, but there's such a huge damage boost to using Booming Blade instead of Extra Attack, that I don't think Inquisitive or Swashbuckler makes sense.  Especially with an 8 in Charisma, Swashbuckler isn't a good option for me.  How does the other melee character taking the Sentinel feat affect my decision about taking Sentinel?  I'm quite interested in listening to you about Sentinel, but you're probably not going to change my mind on Booming Blade and War Caster.

Summary:
Question 1: If I don't take war caster and don't get to cast the Shield spell as a reaction anymore, and don't want to use concentration spells anymore, what spells do I use my spell slots for?
Question 2: How does the other melee character taking sentinel affect my decision about whether or not to take sentinel after taking the war caster feat? (I am assuming that your answer to question 1 won't convince me that war caster is lower priority than sentinel)

Warcaster isn't a terrible feat for you. I just don't know if it's definitely better than Sentinel for the purposes of tanking.  The job of tanking is different from the job of killing lots of enemies quickly.  They can overlap somewhat, but they emphasize different aspects of combat. 

I think you're in a tough bind if you're the de facto party tank.  Warcaster or Resilient (Concentration) are important for you as a melee build with concentration spell usage, but Sentinel is the primary feat to use to keep enemies from running away.  

How about you stay with the Warcaster feat and stay with the Ranger until you pick up 3rd level spells?  Rangers have a slightly better spell slot progression than ATricksters and get some useful options.  Spells like Fog Cloud, Spike Growth, Conjure Animals, and Plant Growth can slow down your enemies or force them to go through you or the Monk to get to the squishier people.  At least delay going Rogue until you pick up Spike Growth.  

Also, have you considered going Eldritch Knight (Fighter) instead of ATrickster?  It's true that you don't get sneak attack damage, but the abjuration spells you do get are better suited to the role of party tank than most illusion spells.  The spell slot progression would be the same and you get to keep having d10 HD, plus the usual Fighter Health Plan.  And you don't lose out on BBlade.

I would get one class to 5 before you multiclass.  If you go ranger to 5, you get a second attack.  If you go rogue to 5 you get another sneak attack dice and a handy thing to do with your reaction to help keep you alive.  Level 5 is a pretty big awesomeness spike.

Generally I think the best way to make enemies attack you is go cavalier fighter.  Short of that I think the best way to go is take the sentinel feat.  If they attack an enemy, you get a free shot against them likely with sneak attack damage added.  If they decided that sucks and attack you, victory!  You also can use your reaction to halve the damage once you get to rogue level 5.  Bonus, they can't run away from you. It's a pretty solid option.

Continuing along the Ranger path is a feasible idea. It removes 2 of the 3 main reasons I want the war caster feat - casting Shield as a reaction and casting Booming Blade as a reaction. I suppose I might still want war caster if i am concentrating on Spike Growth. How do I use that spell properly? Do I cast it to create an area separating the two melee characters from the three ranged characters? Or do I put it in between the enemies and us to force them to take a slightly longer route to reach us?

I did look at Eldritch Knight as a possibility, but I was looking at it more as an alternative to Ranger rather than an alternative to Rogue (because Ranger and Fighter both give proficiency with shields and a fighting style). I also considered Fighter 1 Rogue X and a straight up Goblin Eldritch Knight. But I have already created the character, so I can't change my first three levels.

Second Wind and Action Surge are nice, and 4 levels of Fighter is 4 more HP than 4 levels of Rogue. Rogue gives expertise, sneak attack, and one more cantrip (probably the improved mage hand). It could be interesting to take the protection fighting style and protect the other tank in the party. If I take it up to level 6 I get another feat/ASI which is good because this seems to be a feat heavy build.

Among level 1 spells, just one Abjuration spell fits my character better than Enchantment and Illusion spells do, but I can get Shield as a Rogue anyways. Then Shadow Blade, Invisibility, Blur, and Mirror Image are all nice level 2 Illusion spells. Other than the Ranger spell Absorb Elements, I don't see anything else in Abjuration and Evocation that appeals to me. So let me know what Abjuration and Evocation spells you're thinking of that I should be interested in.

I am sharing party tank responsibilities with the Wood Elf Kensei Monk that has 19 AC with Agile Parry and a +6 to Dex saves. I think he is planning on taking the Sentinel Feat, which decreases the utility of the feat for me. 

Our first two campaigns we had a Paladin with 16AC (using a two handed weapon instead of a shield) and a low AC Circle of the Moon Druid as our twin tanks both times (I didn't like the idea of our second campaign having such a similar party makeup to the first campaign, but I wasn't going to tell people what to play - even worse, both campaigns also had a Rogue and a Wizard, so 4/5ths of our second campaign's party was very similar to the first campaign). This time it's a Ranger and a Monk as twin tanks, so just like the first two campaigns the tanking responsibilities are kind of shared between two guys. 

So I am not the only tank, but just like our first two campaigns, we don't have any pure tank, and I am not trying to be a pure tank either.

Questions:

1) How do I use Spike Growth properly?

2) Other than Shield, what spells make Eldritch Knight a better choice than Arcane Trickster

Bonus question

3) I haven't officially chosen my level 3 spell yet, so I can change it, as well as one replacing one of my already known spells. I know Hunter's Mark and Goodberry, and I am planning to choose Cure Wounds (because I found out that I am also playing the role of party healer). Should I change any of these three spells?

1) You would use Spike Growth to make your foes pay for trying to move around you and your Monk ally.  It both reduces movement speed and does damage.

2) Your are right that there are not a lot of Abjuration spells for 1st and 2nd level slots for the Eldritch Knight.  Counterspell and Dispel Magic are frequently useful, but you also have a Wizard for that.  However, while I understand why you would want illusion spells like Mirror Image and Blur, these just make your character harder to hit.  They don't do anything to protect your Wizard.  Tanks are supposed to take hits to some degree.  That's why they're called tanks.  Think about characters like The Hulk or Deadpool.  They get hit a lot.  

Another path that I have not yet Kendis brought up:  what about the Cavalier Fighter?  That has Party Defense written all over it.  Unwavering Mark at 3rd level lets you mark any creature you hit with a melee attack so that all of its attack rolls versus anybody except you become disadvantaged.  Even if they manage to hit, you can then do a special melee attack against them as a bonus action on your next turn.  Of course, this does decrease the value of Warcaster since you would not be able to get cantrips unless you took Magic Initiate at 8th level. 

Anyway, with the way your stats line up, I don't think you can get everything you want.  You will need to sacrifice some damage output for tankiness or sacrifice some tankiness for damage output.  Sorry. 

So do I cast Spike Growth to the side to try to force enemies to come through the Monk and me?  I can't see casting it in an area where the Monk and I would want to move, because then the spell would slow and damage us.  Maybe the best way to use Spike Growth is to cast it around an enemy, and they take the damage and reduced move speed to get out of the area they're currently in, but once they're out of the area, the spell probably isn't useful anymore?  So I would only need the spell for a couple of rounds before the enemy is out of the area, and I don't need to try to maintain concentration on the spell for 3+ rounds.

I haven't seen any mention of Fog Cloud or Ensnaring Strike, so it sounds like those two spells aren't worth taking and don't help much with tanking.  So I can stick with taking healing spells for my level 1 Ranger, because I am the only one in the party with healing spells right now.

Cavalier Fighter would be a decent path if I went pure tank, but I am not trying to be a pure tank.  I'm more interested in what Ranger abilities and spells I could use for tanking.  I guess their lack of tanking abilities is why no one uses them as tanks.

Getting melee enemies to attack us has been pretty easy, but getting the ranged enemies to attack us instead of attacking our ranged allies is the challenge.  Especially when the Monk uses his deflect missiles ability and catches arrows, the ranged enemies aren't continuing to shoot arrows at him.  For that, we're both trying to use our mobility to get into the face of the ranged enemy, which makes us more threatening, and gives our ranged allies some cover if the ranged enemies want to shoot around the person standing in front of them.  Rogue Cunning Action is going to be useful for that purpose.  It's when we're not next to the ranged enemies that they're ignoring the Monk and me (and melee abilities like Sentinel and Cavalier won't help until we get up next to the ranged enemies).

Fog Cloud seems like one way to limit the effectiveness of ranged enemies without being in melee range of them.  But I don't know if it's worth learning that spell and using a spell slot on it.  Should I let the Wizard and Warlock focus more on ranged crowd control on the ranged enemies?

I was slightly disappointed that I rolled 15,14,12,10,10,8 for my stats, but it's not too big of a problem.  I'm fine with sacrificing tankiness for damage, because I'm sharing tanking duties.

Going into rogue is so difficult to make a decision on where to stop as a multiclass.  For the first five levels in particular each new level has a good use for what you have in mind.  MY personal opinion is take a level of rogue after you reach level 5, and get that extra attack.  After that you can alternate rogue and ranger levels as you see fit.  It might not be an awful idea to take just a single level in fighter for the second wind and the extra fighting style.  The ranger has limited options for fighting style so you could pick up the 'Protection' style from fighter to improve your front line support.  Maybe farther down the line you could decide to pick up Action surge but just the one level would help to round out some of your ideas for your ranger.

If you are itching to multiclass sooner rather than later, I would take 1 Rogue, and 1 Fighter.  Rogue for sneak attack and expertise to give you more of the stalker vibe, and Fighter for the defensive tanky attributes you are aiming for.

As for some of the spells you mention, if you engage the enemy quickly enough you can drop the Spike Growth behind you to prevent them reaching the squishies without penalty.  Fog Cloud to me is best used if you have a group of archers supporting some melee combatants.  Fog the long range guys to force them to move closer (if in a fairly confined area) of just force them to spend time moving in general.  you can also cast the fog Just in front of you so enemies can't see through but as soon as they come out of the fog you are there ready to sneak attack/ambush them.  Ensnaring Strike is a tough one, single target, doesn't work well on big enemies.  May be useful to restrain a mage in the back row, but you could just cut off his line of sight with fog cloud and deal with him that way.  Probably the best use for it is when somebody you want to capture is trying to escape.  Drop the Sword and Board, draw your bow and try to tag Bravely Bold Sir Robin in the back with ensnaring strike as he bravely runs away away.

Action Surge would go so well with the Gloom Stalker's extra attack on the first round of combat.  That could be 6 attacks in the first round of combat.  Which with Cavalier means marking as many as 6 enemies in the first round.  If I was trying to be a pure tank, Cavalier would be great.  

But Rogue is very appealing for the Cunning Action.  Even with 40ft movement speed in the first round of combat, I don't always have enough movement to get to where I want to be.  The extra movement from Bonus Action Dash is also very good for getting in the face of a ranged enemy in later rounds.  The Disengage ability is good if I want to attack one enemy, but to be standing in a different place at the end of my turn - or to just force a melee enemy to move and take damage from Booming Blade.

I've seen a few combats where I can't get the Gloom Stalker extra attack in the first round of combat because I'm going first and there aren't any enemies within 40ft of me at the start of combat.  Having just completed a campaign where I had an Arcane Trickster, I'm really missing being a Rogue (and owning a Longbow - my newly created Human Ranger couldn't afford one).

I can't use both Booming Blade and Extra Attack, I have to choose one or the other each round.  Using Extra Attack instead of Booming Blade seems to be less tanky to me.  Booming Blade won't stop them from moving, but it will make it hurt if they move.  Using Extra Attack doesn't really do anything for my tanking unless I go with Cavalier Fighter.    If I'm using my bonus actions for Cunning Action and my spell slots for Shield, I won't be using Hunter's Mark as much, so the Extra Attack isn't as competitive in damage dealt.  Am I missing something about Extra Attack that would make it a better choice than Booming Blade?  I know it's a better chance to land a Sneak Attack, but I don't see any improvement in my tanking abilities if I get Extra Attack unless I go Cavalier.

Re: Movement speed.  The Longstrider spell is available to both Rangers and Wizards.  No concentration, lasts an hour, adds +10' to your movement.

Re: Fog Cloud.  That is a great inexpensive spell for reducing effectiveness of enemy archers.  Probably better to let your Wizard take it, though, since you're on healing duty.

The value of Extra Attack goes up if you plan to get feats like Polearm Master, Great Weapon Master and/or Sentinel.  It's more useful when you can potentially add rider effects to most of your melee strikes.  

It doesn't sound like you want to go Ranger much past 5th level, but if you get to 9th level, you get Conjure Animals.  That is a very useful spell to add allies to the battlefield.  You can get 4 brown bears, each with multi-attack.  That's a lot of hp to help your party's tanky-ness.  Alternatively, see what your party Wizard feels about getting some summoning spells.  They are not quite as reliable and would be of higher level slots, but Elementals and Fiends could also be useful tanks.    

The extra attack at level 5 isn't a big deal to me. Getting 2nd level Ranger spells is more of an attraction to me than getting the extra attack. 

But I'm not really sure how I would use the 2nd level spells.  I could see myself using Healing Spirit or Lesser Restoration because I'm taking the role of party healer.  I could also see Pass Without Trace being really useful since every single person in our party has +1 dexterity or better and no one wears heavy armor.  None of those spells have any tanking aspect to them, so I wanted to get some input on possible 1st or 2nd level spells that would help me with tanking (such as the advice I got about Spike Growth). 

I think I'm just going to stick with the Level 1 Healing Spells and stop at level 4 in Ranger.  Longstrider is an interesting idea as an alternative to getting Cunning Action, but once I pick up Cunning Action, I don't think I would need it.  It would help with the main weakness the Monk and I have in tanking right now, which is getting ranged enemies to attack us (which is mainly a problem when we're not next to the ranged enemies, which is especially hard if the ranged enemies are smart and aren't all standing next to each other, and are trying to stay away from the Monk and I).

Level 6 giving another favored enemy and another favored terrain isn't a big deal to me.  The level 7 giving proficiency in Wisdom saves is pretty awesome.  

I think Rogue from levels 5-7 is better than Ranger from levels 5-7.  Especially because of Shadow Blade at level 7 (which helps decrease the need for Extra Attack to make sure I get Sneak Attack almost every round).  I do really like Iron Mind at level 7 from Gloom Stalker, but Uncanny Dodge, two more skills with Expertise, Evasion, and Shadow Blade looks better.

Going pure Ranger and getting Conjure Animals at level 9 would be fun, but because it's a concentration spell, I think it would make more sense as a ranged Ranger.  Or as a Druid.

LOL.  Sounds like you're really itching to go Rogue no matter what.  In that case, it probably makes more sense to maximize your stealth.  Instead of being the party tank, you become the party special ops.  IOW, you use Pass Without Trace on the you + the Monk, then the two of you scout ahead to destroy/weaken the enemy's own scouts and archers before the Wizard and Battlemaster show up.  It could potentially leave your Wizard and Fighter without protection sometimes, but scouting ahead seems to me a role that you and the Monk are better suited for given your collective capabilities and inclination.  So you really wouldn't be tanking much, but instead laying the groundwork for your less melee-inclined allies to get up to combat position.  

Good low level ATrickster spells:  Minor Illusion, Silent Image, Suggestion, and the ones you've already mentioned.  With Invisibility + Pass Without Trace, you and the Monk should be able to breeze through most live defenses.  And your Rogue levels will help you get past traps.  

One more note:  Longstrider does not have to be cast on yourself.  So it's a better spell to cast on your Monk b/c of their already substantial move speed boosts as they level up.  

Yeah, I'm definitely itching to go Rogue no matter what.  I did really enjoy playing an Arcane Trickster in the first campaign.

That's an interesting idea to kind of go special ops with the Monk.  It would be a very risky strategy to try to sneak past the melee enemies and go for the ranged enemies, and then hope to draw the melee enemies back towards us and hope that they don't instead turn and head towards our three ranged allies.  But right now the Monk and I have been engaging the melee enemies first, which has quite often resulted in the ranged enemies going after our ranged allies instead of us.  So it is worth trying a new strategy.  The Monk and I do have the stealth and perception to make this work.

I am likely taking Silent Image as a Rogue, even though the Warlock has the invocation (for now at least) that lets him cast it at will.  I don't expect to take Minor Illusion (the Wizard has that), I think the Message cantrip will be useful for communicating with the Monk or with the rest of the party when going special ops.  And then my other two cantrips would be Booming Blade and Mage Hand.

It'll be close to the end of the campaign by the time I get to level 7 in Rogue and can take Suggestion, but I'm probably prioritizing Shadow Blade and Invisibility at that level.

I don't think it makes sense to cast Longstrider on the Monk.  +10ft move speed makes a much bigger difference when you've only got 25ft or 30ft movement, but when you've got 45ft or 50ft movement, it won't make as big of a difference.  

I think I will take the Ranger spell Fog Cloud.  I'll get level 2 spell slots before I get level 2 spells, and Fog Cloud scales nicely when upcasted.  A 40ft radius circle is a lot bigger than a 20ft radius circle.  A 40ft radius circle is pretty huge.  It'll definitely help with eliminating the effectiveness of our ranged enemies, which is something that our party definitely needs.   Does this seem like a good choice given our current struggles with ranged enemies?  

Even with the heavy rogue levels, I would still advocate one level in fighter just to bolster your self and grab the extra fighting style.

Is the Protection fighting style (which would usually only protect the tanky Monk) and the Second Wind ability better than taking another level in Ranger?  Getting to level 5 and getting those level 2 Ranger spells or getting to level 7 and getting proficiency in Wisdom saves or getting to level 8 and getting an ASI and Land's Stride all seem like they would be better than getting the Protection Fighting Style and Second Wind.  Edit: I forgot that level 6 has the bonus of giving another level of spell slots because of the multi-class rules.  That's also a pretty useful boost, even if Favored Enemy and Favored Terrain is a pretty minor boost.

The best way to attact attention is to be dangerous, that is quite easy as a ranger rogue. Since my personal favourite and current char is a gloomstalker5/assassin4/battlemaster1 going gloomstalker5/assassin11/battlemaster 4 I can easily see this blended into more of a tank.

change assassin for swashbuckler and go to town.

i think it would be crazy to not spend 1 level to gain an extra attack, which is arguably the best ability in the game. After all, you deal zero sneak attack damage if you dont hit, and having two chances at landing your big extra dos is huge. In addition hunters mark, flaming weapons and so on gets doubled. Action surge also gets doubled!

this type of character works both as a spec-op, but has a lot of hp, and will draw fire because of it beeing a pain for enemies.

Add in sentinel, healing spirit etc and you are a versitile tank, who can also sneak, deal good consistent damage, cast some spells and pretty much do whatever.

Booming blade is good, and would be worth a feat solely for oppotunity attacks with combat casting.

My problem with Extra Attack is that I have to choose between that and Booming Blade.  If I don't take Booming Blade, then getting Extra Attack (and level 2 Ranger spells) would be an obvious choice.

Swashbuckler isn't a good choice because I have an 8 in Charisma.  

I did consider Rogue Assassin - Ranger Gloomstalker before I created the character, and that would be a character that wouldn't use Booming Blade and would definitely want the extra attack.  It seems quite reliant on getting the surprise round in combat. It would go well with taking the Sentinel Feat because I wouldn't be taking War Caster.  I could talk with the Monk in the party and see if we can come to an agreement to really focus on getting surprise rounds to start off combat, but that might make the three ranged characters feel a bit left out.

With your experience of the Gloomstalker-Assassin combo, do you think this would make a better tank than a Gloomstalker-Arcane Trickster combo?  The ability to get the warcaster feat, and cast Booming Blade as an opportunity attack or to cast Shield as a reaction if they don't run away is quite appealing to me.  Also, it lets me get the Message cantrip to communicate with the rest of the party when I'm scouting ahead in darkness, and near the end of the campaign I can get Shadow Blade to make getting advantage and Sneak Attack even easier.  

If I had rolled a 16+ for one of my ability scores and had chosen a race with +2 dex, the extra attack would be slightly more appealing, because my damage would be 4+ weapon damage instead of 3+ weapon damage.  But instead of being a Wood Elf with 18 Dex and light armor (and likely getting 20 Dex for my first ASI), I'm a human with 16 Dex and Medium Armor master and not as strong an urge to boost my Dex since it won't increase my AC.  I was really hoping for a 16+, but I didn't get one.

Magic Initiate would give the Shield spell, but I could only cast it once per day (and without the war caster feat, I could only cast it if I had the foresight to put away my weapon on my turn).  Going Arcane Trickster with war caster lets me cast Shield four times each day, even more if I use a higher level spell slot for it.  I've seen the Wizards in our first two campaigns use the Shield spell (and also some of our enemies using it, too), and I'm really interested in having the spell.  Boosting my AC to 25 four times a day seems pretty useful.

I do have some time before I have to choose a Rogue Archetype, so I'll keep my mind open to doing Assassin and Sentinel instead of Arcane Trickster and Warcaster.  What are your thoughts on using Assassin instead of Swashbuckler or Arcane Trickster?