Steps to reproduce:
1. Enter Dank Crypt
2. Use Shove or Throw to stack up Entombed Scribe / Entombed Warrior corpses into a nice neat little pile.
3. Cast an Area of Effect spell (Cloud of Daggers, Moonbeam, etc) onto the pile of corpses
4. Click the button to open Withers' tomb (aka Hooded Skeleton)
The Entombed Scribes / Warriors will rise from the dead .. sustain damage .. but will not die. Instead they will have 0 hit points.
On their turn it will say "Plotting next move ..." and sit there.
If memory serves, in Patch 6 it was also hard to kill them too .. but in Patch 7 you can just throw them and the damage from being thrown will kill them.
I can reproduce this 100% of the time.
Best of luck
Dan