I’ve had this problem for the last week and haven’t been able to pin it down. Basically one of my creatures frequently freezes the game when they attack. They have many cast on hit gems etc. Its the Vital Clutcher monster in the first slot of my team that triggers it.
Any time they attack, there’s a good chance the game will freeze, particularly at the end of a battle.
It’s some combination of the artfifact and spells, as the previous monster using a similar setup of spell gems with the same artifact also froze the game.
Uploading my save, hopefully you can pin it down.
slot1.sav (256 KB)