I aviced this to the other players before, in another thread:

Until this issue with thrall fall damage is solved and fixed, DO NOT TELEPORT TO THE SINKHOLE WITH YOUR FOLLOWER.

It’s maybe 1:1 he will teleport behind you, hit the ground for few thousand fall damage and if he won’t teleport back to you quickly, the Dracosaurus down there will finish him, triggered to attack by a player in that area.

As I said before, My Lianeele has something around 4500 HP, armor value around 1600 and got straightforward 3500 damage right after teleporting to Sinkhole and then spawning next to me again. She had full life bar before teleporting.