Gamebreaking bug

[trulygenericname]

I am currently encountering a bug where an enemy will cast a spell, it will randomly deal 0 damage, and it will instantly kill an entire stack of units. These can not be resurrected either. They just instantly die. This has happened so far from the following effects: Fireball, Ice Snake, Poison Skull, Geyser, burning, poisoning, freezing.

This is frustrating as it forces me to kill units of 1 skeleton archer so that they don't kill my stack of 50 rune mages. And it makes many spellcasting heroes even more frustrating than normal.

Is there any fix for this?