Rahab reset when someone leaves map

In middle of killing, or sometimes even just starting the battle, rahab randomly resets back to full hp and back to phase 1. All bad effects from him like phase 3 no potion curse remains as well. I have faced this bug countless times and finally decided to make a bug report on it.
My last run was going smoothly until phase 3 started and someone in the altar at rahab leaves the map and rahab completely resets, leaving us starting to kill again from phase 1, with no potions allowed.
I cant reproduce the bug at will, but it keeps happening every few runs especially in randoms where people keep randomly leaving.

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