Bonemass is the fight that stops more Valheim runs than any other. He is a huge blob of corpses with a poison cloud and a lot of health. He is also completely beatable the moment you bring the right two things.
Those two things are a blunt weapon and poison resistance mead. Bring both and this becomes one of the easier bosses. Bring neither and you will not scratch him.
Boss fightBonemass
- Summon with
- 5
Withered bone at his altar in the Swamp - Weak to
- Blunt. He heavily resists pierce and slash, so arrows and swords are close to useless.
- Take with you
- An iron mace, poison resistance mead, and your best shield
- Drops
- Wishbone, which finds silver and buried treasure
What he does, and what you do
- Poison cloudTell: He hunches and a green cloud spreads out from himThis is what actually kills people. Poison resistance mead reduces it enormously. Drink one before you start and another the moment the first runs out. Do not stand in the cloud if you can help it.
- Ground slamTell: He raises both arms over his headBack out of range. It hits hard and it staggers you, which is how you end up stuck inside the poison cloud.
- Summoned skeletonsTell: He calls for help mid-fightIgnore them if you can and keep hitting Bonemass. Killing adds wastes your mead timer, which is the real clock on this fight.
Why a mace and nothing else
Damage types matter more in this fight than any other in the game. Bonemass resists piercing and slashing damage so heavily that a bow or a sword feels broken. Blunt damage goes straight through. An iron mace is the standard answer and it is worth making one purely for this.
The plan
- Make an iron mace and bring a full stack of Poison resistance mead.
- Eat three of your best health foods before you summon him.
- Drink a mead, summon, and go straight in. He is slow, so you can out-walk him.
- Hit, step back when he raises his arms, hit again. Re-drink mead the instant it expires.
- Keep the Eikthyr power up for stamina if you have nothing better.
What you get
The 
Wishbone. Wear it and it pings when you walk near buried silver or treasure, which is the only practical way to find silver in the Mountains. His power also gives you a big physical damage resistance boost, which is superb for melee fights.
Boss number three down. On to the mountains.
