A giant poisonous blob in the Swamp — the difficulty wall of the early game. Bring poison mead or don't bother.
| Offering | 10× Withered bone |
| Where to find it | Withered bones come from Muddy scrap piles inside the Sunken Crypts (you'll be mining these for iron anyway) and from Swamp chests. Ten is a low bar once you're crypt-diving. |
| Altar location | His altar is out in the Swamp. The Vegvisir is found inside Sunken Crypts and occasional ruined Swamp structures. |
| Boss HP | 5,000 |
| Recommended gear | Iron armour, an Iron shield, and a blunt weapon — an Iron mace, or even better the Frostner if you've reached silver. And Poison Resistance mead. |
| Weak to | 🔨 Blunt and 🧊 Frost — a mace or Frostner hits both notes. |
| Resists | Slash; very resistant to 🔥 Fire and 🏹 Pierce (bows are nearly useless here). |
| Immune to | Poison, Stagger. |
Attacks to watch
Step-by-step strategy
Poison Resistance mead is near-mandatory — the whole fight is balanced around it. Drink one before you start and re-drink as it expires.
Flatten the ground around the altar with a hoe first — it kills the swamp's uneven footing and keeps leeches out.
Best weapon is the Frostner (blunt + frost = double weakness). No silver yet? An Iron mace or two-handed Stagbreaker/Iron sledge works — and the sledge's AoE clears his summoned adds.
A classic safe method: climb onto the altar mound and swing down at him, using knockback to keep skeletons off you.
Leave the bow at home — he's very resistant to pierce and fire. Frost arrows are the only semi-decent ranged option.
📷 Screenshots coming for these spots:
| Trophy | Bonemass trophy |
| What it unlocks | The Wishbone — wear it and it pings toward buried Silver veins in the Mountains (plus muddy scrap and buried treasure). It's effectively required to progress the Mountain biome. |
Bonemass is boss 3 of 7 — the Swamp Forsaken. The Mountains and Silver — the Wishbone is how you actually find silver ore, which gates the entire Mountain gear tier.
See the full kill order, every summon item, and a tick-off tracker on the Valheim bosses hub.
One Forsaken down — here's the rest of the run.