I should have said it was Rogue Assassin. Also, I will be taking the Rogue to level 4 as I get another feat at 4 (too close to pass it up).
After looking more into it and speaking with others, if I was to go for a 3rd class then it makes sense to go Fighter 2 for Action Surge.
But if I did that then I would have 4 on rogue and only leaving room to go Gloomstalker Ranger 14, missing out on shadowy dodge at 15.
Don't worry about what your build will look like at 20, worry about what it will look like at 11. 20 is a pipe dream that you will either never reach, or play very little of, but 11 is close enough, and an important benchmark where you don't want to feel behind.
Nothing wrong with going Rogue 4 for the ASI and then going back to ranger to have Iron Mind by 11. Wisdom save proficiency is incredibly important. Don't skimp on those defenses in the name of damage. Guess how much damage you deal when you're paralyzed?
The fighter dip for Action Surge has obvious synergy and IS great with Dread Ambusher, but I think at this point you deal plenty of damage. I would consider it after Gloomstalker 11/ Rogue 4 if you're still playing the character and want a way to feel important again while the casters are breaking the world.
I'm currently playing a Scout/Gloomstalker and its my favorite character I've played in a LONG time. I wouldn't add another class personally. Just decide how high you want to go in Ranger (5, 7, 8, & 9 all have decent reasons) and go all Rogue for the rest. Personally I think Scout is a better all around subclass for rogue but I understand the attraction to assassin.
I'll go Ranger 5, then Rogue for a long while and at some point grab two more levels of Ranger for a total of 7. The higher level rogue and scout abilities seem better to me than the Ranger/Gloomstalker ones
It seems like you might not have the stats for it and I’m sure people will disagree with me here, but if you have at least 13 Strank‘s, going barbarian is not the craziest thing to do and in certain situations could be just what you need to show her out your weaknesses and improve your strengths… I know I’m gonna get some flack for this and people might disagree but why not mention it…?
rage allows you to take half damage from most sources. When you combine this with things like uncanny dodge and evasion, you get some pretty crazy damage reduction. And for a high damage range character that’s lurking in the darkness that most people can’t even see, your one weakness would be something with tremor sense or Blindsight or true sight rolling right up to you and stopping your shenanigans. It’s kind of the one thing that can really kill you. Dipping barbarian stops this from being such a deadly possibility for you… As a ranger, especially when multi classed, doesn’t rely very heavily on spells but does use cool things out of combat like pass without trace… This actually synergize as well with barbarian rage because you will cast all those awesome ranger spells outside of combat and long strider lasts one hour which is pretty cool and it doesn’t require concentration… Then you rage when you’re in combat and are an evasive, unstoppable, tanky, Mobile, invisible without concentration because of gloom stalker, sniper turret.
this is where people might especially not like this idea or love it but technically the ancestral guardian sub class can be used at range, you can strike from the shadows where the enemy can’t see you, while you are raging, and give the enemy disadvantage on hitting everyone but you as ancestral guardian spirits surround the enemy you just shot in the darkness, aLl while you are busy being invisible in the shadows because you’re a gloom stalker and you’re far away at range and they might not even be able to get to you. It’s an insane debuff and you’re dealing very high damage.
Again, people might disagree with me, three classes multi classing is a lot, you might not have the strength stat requirement anyway, and your DM might not let you use ancestral guardian effect at range even though I think technically RAW you can… but I wanted to give this idea a shout out.
Don't worry about what your build will look like at 20, worry about what it will look like at 11. 20 is a pipe dream that you will either never reach, or play very little of, but 11 is close enough, and an important benchmark where you don't want to feel behind.
Nothing wrong with going Rogue 4 for the ASI and then going back to ranger to have Iron Mind by 11. Wisdom save proficiency is incredibly important. Don't skimp on those defenses in the name of damage. Guess how much damage you deal when you're paralyzed?
The fighter dip for Action Surge has obvious synergy and IS great with Dread Ambusher, but I think at this point you deal plenty of damage. I would consider it after Gloomstalker 11/ Rogue 4 if you're still playing the character and want a way to feel important again while the casters are breaking the world.
I'm currently playing a Scout/Gloomstalker and its my favorite character I've played in a LONG time. I wouldn't add another class personally. Just decide how high you want to go in Ranger (5, 7, 8, & 9 all have decent reasons) and go all Rogue for the rest. Personally I think Scout is a better all around subclass for rogue but I understand the attraction to assassin.
I'll go Ranger 5, then Rogue for a long while and at some point grab two more levels of Ranger for a total of 7. The higher level rogue and scout abilities seem better to me than the Ranger/Gloomstalker ones
Have a blast
It seems like you might not have the stats for it and I’m sure people will disagree with me here, but if you have at least 13 Strank‘s, going barbarian is not the craziest thing to do and in certain situations could be just what you need to show her out your weaknesses and improve your strengths… I know I’m gonna get some flack for this and people might disagree but why not mention it…?
rage allows you to take half damage from most sources. When you combine this with things like uncanny dodge and evasion, you get some pretty crazy damage reduction. And for a high damage range character that’s lurking in the darkness that most people can’t even see, your one weakness would be something with tremor sense or Blindsight or true sight rolling right up to you and stopping your shenanigans. It’s kind of the one thing that can really kill you. Dipping barbarian stops this from being such a deadly possibility for you… As a ranger, especially when multi classed, doesn’t rely very heavily on spells but does use cool things out of combat like pass without trace… This actually synergize as well with barbarian rage because you will cast all those awesome ranger spells outside of combat and long strider lasts one hour which is pretty cool and it doesn’t require concentration… Then you rage when you’re in combat and are an evasive, unstoppable, tanky, Mobile, invisible without concentration because of gloom stalker, sniper turret.
this is where people might especially not like this idea or love it but technically the ancestral guardian sub class can be used at range, you can strike from the shadows where the enemy can’t see you, while you are raging, and give the enemy disadvantage on hitting everyone but you as ancestral guardian spirits surround the enemy you just shot in the darkness, aLl while you are busy being invisible in the shadows because you’re a gloom stalker and you’re far away at range and they might not even be able to get to you. It’s an insane debuff and you’re dealing very high damage.
Again, people might disagree with me, three classes multi classing is a lot, you might not have the strength stat requirement anyway, and your DM might not let you use ancestral guardian effect at range even though I think technically RAW you can… but I wanted to give this idea a shout out.
Hope you’re having fun!