Bonemass

Bonemass is a boss creature in Valheim, a massive swamp-bound undead mass fought as a major progression gate. It has 5000 health and threatens players with powerful area-of-effect poison attacks, along with a heavy punch that deals blunt and poison damage. It is highly resistant to physical tools and weapons, including chop and pickaxe damage, making the fight centered on poison resistance, mobility, and sustained combat preparation. Bonemass is one of the game’s key biome bosses and serves as a milestone encounter in the swamp progression path.