Deathslicers are immune to all known damage types that players can attack with. However, if someone manages to kill one of them, it will respawn immediately after dieing. Note that they are pushable.
Damage Taken From Elements
Deep in Tarpit Tomb, Formorgar Mines during Ghazbaran's raid.
Use a stronger monster such as a Demon to destroy it, when it's trapped. You can push it.