One of two things. Either I am doing it wrong or the Githyanki fight is too difficult for the current level. Every time combat is initiated, of which can not be avoided save never letting Lah'Zael get near them in the first place, They get the drop everytime and wipe out half my party and nearly killing the other half before I can even act. And that is from just 2 of the Gith.
So again, either I am doing it wrong or there is something wrong with the encounter that needs fixing.
Any suggestions?
Its the hardest fight in the game up there with the bullette. They are level 5 which means they get multiple attack's per round so they are ahead of you on the action economy.
There is no way around it, you need to buff the hell out of your party. This is where Potions of speed need to be saved for, as well as Hill giant strength.
First you will want to Unlink your team and put some of them on top of the bridge and along the path to the left of the bridge leading down. You want to throw some grease along those paths.
You will want to make sure the whole team has plenty of healing and greater healing potions.
Whoever you send down there needs to be able to either misty step out, turn invisible, or escape quickly and that includes Lae'zel as you both need to make sure you are not surrounded.
Keep the mobs in front of you at all times to avoid having them get advantage on you. Thunderwave is incredibly effective at knocking them backwards off the bridge. Spells that create surfaces that impede movement are also incredibly helpful. Dissonant Whisper is amazing if you have it. if you have Lae'zel kitted out at a Battle Master you will want to make sure riposte is active and frightening attack ready to go. What does your party makeup look like?
Summoned familiars are a huge help here since they help you balance out the action economy.
Party makeup and equipment should be at peak. Max out armor class. use Mage armor. use mirror image.
I love this fight but you are right its incredibly difficult.