So for the fight where they are in the room with the dead illithid, I crawled up the ladder outside the room on the platform, cast grease on the doorway leading into it, and then sneak attack bow shot the weakest one and killed him and remained hidden and got another sneak attack shot off. After that, they came around the corner and the AI hates things like grease, so they just bunched up at the doorway. I cast bless on everyone and then used the illithid power to create an inky cloud, obscuring us all and giving them disadvantage on attacks. I would then cycle my guys out, 1 by 1, to shoot out of hiding and go back into the cloud. When they were grouped id throw ice and poison down (not fire because it burns the grease away,thats only if they walk onto it). When the hobgoblin came out, I cast hold person on him (dropping the bless, both concentration) and murdered him.
I think I got hit 3 times or something. Gotta play with the environment and bottlenecking. If there are a lot of archers, use the illithid reflect power, it works against the bottles they throw too so theyll fire bomb and poison and acid themselves chucking stuff at you.