Bonemass is the third boss you’ll encounter in Valheim, the popular Viking survival game on Steam. It is one of the more difficult bosses you’ll face in your journey so far, especially if you are progressing through the game as its designed. You’ll want to gather a few items and utilize one type of weapon, in particular, to trounce this boss. Here’s how to summon and defeat Bonemass in Valheim.

How to Summon Bonemass in Valheim

To summon Bonemass in Valheim, you’ll need to offer the following materials at the sacrificial altar:

  • Withered Bone x10

You can gather Withered Bone from inside of the Sunken Crypts in the Swamp biome. These are the dungeons that have green torches out front, which require a Swamp key to open. You’ll sometimes see them lying around inside the crypts and also inside the Muddy Scrap Piles.

Muddy Scrap Pile Valheim

You will also find the stone to locate the Bonemass summoning location inside of the Sunken Crypts. Explore these dungeons thoroughly to collect Iron and Withered Bones. 

How to Defeat Bonemass in Valheim

To defeat Bonemass, we recommend gathering the following items per character in your party:

  • One blunt weapon: Iron Mace or Bronze Mace (Lvl. 2)
  • One shield: Bronze or better
  • 4 Poison Resistance Mead
  • 4 Medium Healing Mead

Unlike The Elder and Eikthyr, Bonemass is a melee fight. Bonemass is weak to blunt weapons, so everyone in your party should have an Iron Mace or the equivalent Bronze Mace level two. Bonemass has a melee attack, a poisonous area of effect ability, and a blob summoning skill. The melee attack can be blocked with a shield, assuming you have proficient blocking skill.

The idea is to block Bonemass’s melee attacks and unleash attacks with your blunt weapon while the boss is staggered. If you are playing with a group of people, whoever has aggro should primarily worry about blocking while the other two attack from behind. Look out for the boss’s poison AoE animation, and leave the area if you don’t want to get poisoned.

Ensure you always have your poison resistance mead active, which lasts for ten minutes. You should kill the boss before the duration is over, but you have extras if you die. When you get low on health, pop your healing mead to regenerate your health. 

You can also effectively deal damage to Bonemass utilizing frost arrows, though we’ve found the blunt weapon melee strategy to be a bit faster. Another thing to consider is clearing out the surrounding mobs in the area before summoning Bonemass. Make sure you have a camp nearby because, like any boss battle, you may die unexpectedly. Running back as quickly as possible will ensure a smooth fight for you and your party.