The Githyanki will be able to ride or summon young red dragons into combat.
Be able to battle a beholder or a lich.
With lv cap = 10? A Lich Challenge Ratting is 21.
https://roll20.net/compendium/dnd5e/Lich#contentI rather not having liches ultra nerfed to fight than having then nerfed to be able to be defeated by a mid level party. Just like on BG1 you don't fight dragons. Only Wyverns. And even on BG2, takes a very long time until you fight true dragons.