I still need to collect more detailed information about using skill cause crash, have u tried to run as administrator?
When u defeated some mobs didn't punish you game over but some does, but in next update all mobs will cause gameover.
Rave vs Krosch scene isn't a bug, it's intended for easier approach.
Krosch don't do much damage because his offensive base stats are low, but he had the capability to tank some damage from his elemental typings and good defenses base stats, I will adjust this issue in the next release.