Forge version: 14.23.2759
Twilight Forest version: 3.8.564
Link to crash log: https://paste.dimdev.org/ucufenirac.mccrash

Steps to reproduce:

1. Go into the dimension
2. Try to cut off the Hydra's head and fight it

What I expected to happen:
I expected to be able to kill the Hydra without crashing.

What happened instead:
I crashed when I was trying to fight it.

Unable to reproduce with the modpack Do I am Cake?. You might be clashing with another mod that's adding something to the Hydra Head entity, but I'll have to look into what might even be causing this.

Might be fixed by 8855626, though it's hard to be sure without a reproduction.

Closing this as 3.8.689 has been released on CurseForge. It can be reopened if people run into the same crash in that version, otherwise it can be considered fixed.