Swamp · location
Bonemass's altar
In a world
5
in 1,000 worlds, of 5 tried
Nearest to spawn
2.8 km
1 world in 10 under 2.2 km
Altar and doors
Boiling Deathtakes 
10× Withered Boneand calls 
Bonemass
Runestones and signs
COOK THEIR REMAINS
Source: location prefab Bonemass in Valheim 1.0.17 (2026-10-05).