Withered Bones are one of those Valheim items that sit in your inventory doing nothing until you learn what they unlock. They are huge, they weigh almost nothing, and they exist for exactly one reason: summoning Bonemass, the third boss. The catch is that they only turn up in one place, and that place is locked behind the second boss.
Quick answer: Kill The Elder for the Swamp Key, unlock a Sunken Crypt in the Swamp, then mine Muddy Scrap Piles, open chests, and smash Body Piles until you have ten Withered Bones.
What you need before farming Withered Bones
Sunken Crypts are sealed behind iron gates, and no amount of hitting them will help. Bring the following before you set out:
- The Swamp Key, dropped by The Elder. That boss is summoned in the Black Forest with three Ancient Seeds.
- A Bronze Pickaxe or better. It costs three Core Wood and 10 Bronze Ingots, with Core Wood coming from pine and fir trees.
- Bronze-tier armor and a blunt weapon. Draugr and Blobs guard the crypts and the ground around them.
- Poison Resist Mead and healing mead. Blobs poison you constantly inside the tunnels.
Pickaxes wear down fast on Muddy Scrap Piles, so carry a spare if you plan to clear a whole crypt in one trip.
Where to find Sunken Crypts in the Swamp
Sunken Crypts are small stone dungeons scattered across the Swamp biome, and they are not subtle. Look for a squat stone doorway with green torches burning at the entrance. The glow reads clearly through the fog and rain, which is usually how you spot one before you spot the Draugr standing next to it.
Walk up to the Iron Gate and interact with it. With the Swamp Key in your inventory, it opens and the SUNKEN CRYPTS label appears as you step inside. From there the layout runs downward into branching mud tunnels, and everything you need is below ground level.
If you are carrying an Iron or Bronze Pickaxe, you can also mine through the crypt stairs to open up shortcuts between chambers.
Three ways to get Withered Bones inside a crypt
| Source | How to break it | Also drops |
|---|---|---|
| Muddy Scrap Pile | Pickaxe | Scrap Iron, Leather Scraps |
| Chest | Hold E to loot | Ancient Bark, Iron Arrows |
| Body Pile | Melee weapon | Stops Draugr spawns |
Mining Muddy Scrap Piles
Muddy Scrap Piles are the lumpy brown mounds packed into the crypt floors and walls, and they are your main supply. Swing a pickaxe at one and it breaks apart over several hits, dropping Scrap Iron and Leather Scraps on most swings and a Withered Bone on some of them. The drop is random, so a single pile might give you none or two.
Because the drop is not guaranteed, volume matters more than luck. Clear every pile you pass rather than stopping once you have a bone or two, and keep an eye on your Pickaxes skill climbing as you go, since higher levels mean fewer swings per pile.
Looting chests
Chests are tucked into side rooms and dead ends throughout the crypt, usually with something unpleasant standing nearby. Hold E to stack the contents straight into your inventory. Alongside Withered Bones you will pull out Ancient Bark and Iron Arrows, both worth the detour on their own.
Destroying Body Piles
Body Piles are the glowing green heaps of bones that keep pumping Draugr into a room. Breaking one shuts off the spawner and can drop Withered Bones in the process, so the thing making your life difficult is also part of the payout. Deal with the Draugr already on you first, then focus the pile.
How many Withered Bones you need for Bonemass
Bonemass costs ten Withered Bones per summon. Head to the boss altar in the Swamp, marked by a giant glowing green skull you will not miss, and sacrifice the bones there. The offering prompt only appears once you are holding all ten, so a short count in your inventory is the check that matters before you sail out.
| Detail | Value |
|---|---|
| Item type | Key |
| Weight | 1 |
| Max stack | 30 |
| Spawn code | WitheredBone |
Each summon consumes the full set, so if you die and need a second attempt, you are farming another ten. Banking twenty on your first crypt run saves a return trip. On PC, the item can also be created with devcommands in the F5 console followed by spawn WitheredBone, though that flags the item as summoned through cheating means in its tooltip.
Faster crypt runs
The bottleneck is never the bones, it is the Scrap Iron you pick up alongside them. Iron cannot go through portals, so park a longship or karve right outside the crypt entrance and dump your haul into it between trips. That turns one crypt into a single uninterrupted clear instead of four nervous walks back to base.
Once you have smelted enough Scrap Iron, upgrade to an Iron Pickaxe before the next run. It chews through Muddy Scrap Piles faster than the bronze version, which means more piles broken per crypt and more chances at a bone.
Ten bones usually come out of one thorough crypt, and everything else you drag back — iron, bark, arrows — is what you will be wearing and shooting when Bonemass starts throwing poison at you. Farm both at the same time and the boss fight becomes the next thing on the list rather than another week of prep.
