Applies to Valheim 1.0, patch 1.0.21 (released on Steam October 28, 2026). Boss, item and spawn numbers come from the community Valheim Wiki. Patch details come from Iron Gate's 1.0.21 notes.
Bonemass is the third Forsaken and the boss of the Swamp, and he punishes one specific mistake: showing up with the wrong damage type. He has 5,000 health, he is weak to Blunt and Frost, and he takes only 25% damage from Pierce and Fire. At skill 30, a maxed Huntsman Bow with Fire arrows needs around 411 shots. A maxed Iron Mace needs about 60 swings.
This guide covers how to farm 10 Withered Bones, where his altar spawns, what each of his three attacks does, and which weapon kills him fastest. There's also a fix for the mistake that wastes your Root Mask.
Quick answer: To beat Bonemass in Valheim, place 10 Withered Bones on his Forsaken Altar in the Swamp. A Vegvisir in a Sunken Crypt marks the altar on your map. He has 5,000 HP, is weak to Blunt and Frost, very resistant to Pierce and Fire, and immune to Poison and Stagger. Drink Poison Resistance Mead before the fight, wear Iron armor, and use an Iron Mace. Stay behind him, run when he leans back, and kill minions as soon as they land. He drops his trophy and the Wishbone.
What do you need before fighting Bonemass?
Bonemass comes right after The Elder in the Valheim boss order. The Elder drops the Swamp Key that opens Sunken Crypts, so start with our Elder guide if you don't have it. Our Swamp guide covers surviving the biome itself.
Have these sorted before you place the bones:
- Poison Resistance Mead. Bring two or three. Each lasts 10 minutes and has a 10-minute cooldown. One batch takes 10 Honey, 5 Thistle, 1 Neck Tail and 10 Coal at a Mead Ketill, then two in-game days in a Fermenter, and makes six meads. Start it before you need it.
- A Blunt weapon. The table below has swing counts for each one.
- Iron armor, if you can afford it. It's the best protection available at this stage.
- Three strong foods, plus healing meads. Serpent Stew (80 health) or Sausages (55 health), Black Soup (50 health) and Turnip Stew (55 stamina) make a solid Swamp-tier mix. Our Valheim food guide has the options by biome.
- The Rested buff. Rest by a fire under a roof before you leave, because Rested speeds up your regen and Wet slows it down. Our comfort guide explains how to stretch it.
- A portal near the altar. Withered Bones are teleportable, though the Scrap Iron you collect on the way isn't. The portal also gets you home for repairs, since Iron gear needs a Forge at level 2 and a Workbench can't fix it.
- Daylight. You'll be Wet the whole fight, and nights in the Swamp add Cold and Wraiths on top.
The wiki's boss strategy page is blunt about the mead: "The fight is balanced around the expectation that players will use Root Mask or Poison Resistance Mead." Treat that as a requirement unless you've already learned the fight.
What are Bonemass's stats, weaknesses and resistances?
These are base (0-star, single-player) values from the wiki's Bonemass page.
| Stat | Value |
|---|---|
| Health | 5,000 |
| Summon | 10 × Withered Bone at his Forsaken Altar (Swamp) |
| Weak (150% damage) | Blunt, Frost |
| Resistant (50%) | Slash |
| Very resistant (25%) | Fire, Pierce |
| Immune | Poison, Stagger |
| Drops | Bonemass trophy, Wishbone |
| Forsaken Power | −25% Blunt, Slash and Pierce damage taken, −100% block stamina cost, +5 stamina per block, 300 s |
Two entries on that list decide your whole plan. Pierce and Fire resistance rule out the bow and Fire arrow kit that carried you through the Black Forest. The Stagger immunity means parrying blocks the punch but won't open a double-damage window.
How do you get 10 Withered Bones?
Withered Bones come from Muddy Scrap Piles inside Sunken Crypts, and from chests in the Swamp. Each crypt pile has 30 segments, and each segment has a 2.86% chance of dropping a bone, which the wiki puts at 0.86 bones per pile.
So plan on about 12 piles for 10 bones. Those same piles average 4.3 Scrap Iron each, so a bone run also yields roughly 50 Scrap Iron, enough for an Iron Mace and more besides. That's why you should farm bones and iron together rather than as two trips.
Any pickaxe works, since piles have just 5 health per segment. The Swamp Key isn't consumed, so one key covers every crypt. Buried outdoor piles are a poor source of bones at 0.06 per pile, and you need the Wishbone to find them anyway. Our Valheim ores guide covers the rest of the iron chain.
Scrap Iron can't go through a wood Portal, so haul it by boat or cart. A Withered Bone weighs 1 and stacks to 30, so 10 of them barely register.
How do you find Bonemass's altar?
Every world has five Bonemass altars, spaced at least 3,000 meters apart and at least 2,000 meters from the world center (wiki: Forsaken Altars). You only need one.
Read a Vegvisir to mark one on your map. They appear in Sunken Crypts and Swamp ruins, so you'll likely find one on your bone run. The altar is a huge skull with a boiling green pool in its jaw, and the runestone beside it reads "COOK THEIR REMAINS."
Before you summon, spend five minutes with a Hoe. The wiki says leveling or raising the ground around the altar gives you better footing and keeps Leeches out of the fight. It's the cheapest upgrade in this guide.
What attacks does Bonemass use?
He has three attacks, and only one of them is about timing. His aura also forces rain, so you stay Wet (−25% health regen, −15% stamina regen) even if you lure him away.
| Attack | Damage | Cooldown | Range | What to do |
|---|---|---|---|---|
| Poison cloud | 130 Poison | 30 s | Used within 15 m, 9 m radius | Run the moment he leans back |
| Punch | 80 Blunt + 50 Poison | 7 s | 8.5 m, 66° front arc | Stay behind him or roll through it |
| Throw | Spawns 4 Skeletons or Blobs | 50 s | Used within 30 m | Kill them as they land |
Poison cloud. He leans backward, then vomits ooze. It can't be blocked or dodged, and the cloud lingers for 15 seconds, refreshing your poison while you stand in it. The cloud centers on where the vomit lands, so it barely reaches behind him. That's your safe spot, and you can still hit him from there. The wiki notes that rolling is often too slow here, so sprint.
Punch. This swipe also carries 1,000 Tier 0 Chop and Pickaxe damage, so it can flatten the trees and rocks you're hiding behind. Parrying works, but you get no stagger from it.
Throw. He reaches into his armpit and lobs a glob that spawns four minions, each with equal odds of being a Skeleton or a Blob. The cap is eight of each, and he keeps throwing at the cap. The wind-up is slow, so you get free hits if nothing else is on you.
How much does poison resistance actually help?
Far more than 75%, and this is the part most guides skip. The wiki's strategy page says either the Root Mask or the mead cuts poison by 75%, but the item pages disagree: the mead is "very resistant" (75% less) while the Root Mask is only "resistant" (50% less).
Armor then works on what's left. The wiki's Damage page confirms that "Poison damage is also reduced by armor," and armor gets far stronger once it's at least half of the incoming hit. Here's a maximum-roll poison cloud in quality 1 Iron armor (our calc, using the wiki's formulas; rounding can add a tick):
| Your protection | Total armor | Poison cloud taken | Duration |
|---|---|---|---|
| None | 42 | 88 | ~22 s |
| Root Mask (replaces Iron Helmet) | 36 | 29 | ~14 s |
| Poison Resistance Mead | 42 | 6 | ~7 s |
| Mead + Root Mask | 36 | 7 | ~8 s |
That last row is the trap. Resistances don't stack, because the strongest source simply overrides the rest. If you're drinking mead, the Root Mask adds no poison protection, and it costs you 6 armor, so keep your Iron Helmet on.
Timing matters too. The wiki's Poison page confirms resistance applies when the poison starts, not on each tick. Drinking the mead after you're poisoned won't shrink that poison, so drink it before you summon him. Poison doesn't stack either: a new hit only replaces your current poison if it deals more than what's left.
What is the best gear for Bonemass?
Bring an Iron Mace. It's the best damage you can realistically craft at this stage, and it costs just 20 Iron, 4 Wood and 3 Leather Scraps. Numbers below are our own estimates: skill 30 in the matching weapon skill (Clubs, Swords or Bows, average damage factor 0.58), with the 2× third hit averaged into one-handed combos. Real fights run longer, since you'll spend time dodging.
| Weapon | Damage vs Bonemass (listed) | Estimated hits to kill |
|---|---|---|
| Frostner, quality 4 | 159.5 | ~41 |
| Frostner, quality 1 | 132.5 | ~49 |
| Iron Mace, quality 4 | 109.5 | ~60 |
| Iron Mace, quality 1 | 82.5 | ~79 |
| Iron Sledge, quality 4 | 109.5 | ~79 |
| Bronze Mace, quality 4 | 79.5 | ~82 |
| Huntsman Bow + Frost arrows | 95–97 | ~90 arrows |
| Iron Sledge, quality 1 | 82.5 | ~105 |
| Stagbreaker, quality 4 | 58 | ~148 |
| Iron Sword, quality 4 | 36.5 | ~178 |
| Huntsman Bow, quality 4 + Fire arrows | 21 | ~411 arrows |
The wiki calls the Frostner the ideal weapon, since its Blunt and Frost both hit his weaknesses, and his neutral Spirit resistance lets its Spirit damage through too. But its Silver recipe is very hard to reach before you own the Wishbone, so it's really a rematch option.
The Iron Sledge does the same listed damage as the mace, but it needs 30 Iron, 10 Ancient Bark, 4 Ymir Flesh (480 coins from Haldor) and a Draugr Elite Trophy. It earns that cost on crowds, because its 4-meter slam hits every minion around you. If you'd rather not pay, a Stagbreaker makes a cheap minion-clearing sidearm with the same 4-meter slam.
For armor, here's a maximum-roll punch with both its Blunt and Poison added up (our calc, no block). The mead shrinks the punch too, because it cuts the 50 Poison down to 12.5 before armor applies:
| Armor | Total armor | Punch taken, no mead | Punch taken, with mead |
|---|---|---|---|
| Bronze or Root, quality 1 | 24 | 106 | 68.5 |
| Bronze or Root, quality 4, or Iron, quality 1 | 42 | 88 | 50.5 |
| Iron, quality 4 | 60 | 70 | 35.7 |
Set your Forsaken Power to Eikthyr for the −60% stamina cost on running and jumping, since this fight is mostly repositioning. See our Forsaken Power tier list for the full ranking.
How do you beat Bonemass, step by step?
- Prep the arena. Hoe the ground flat, then build a small shelter and a portal nearby.
- Summon in the morning. Activate your Forsaken Power and drink your mead first, then place all 10 bones.
- Get behind him. Circle to his back and start your combo. His punch covers his front arc, and his cloud barely reaches behind him.
- Watch for the lean. When he tips backward, stop swinging and run. Come back once the cloud thins out.
- Clear minions first. When the glob lands, turn around and kill what spawns. Skeletons and Blobs will overwhelm you if they stack up, and each Blob's cloud adds 90 Poison.
- Repeat, and re-drink. Your mead lasts 10 minutes, exactly as long as its cooldown, so drink the next one as soon as the first runs out.
If you die, he stays up, because a summoned boss doesn't despawn until it's defeated. Eat, recover your gravestone and go again.
Is there an easier way to kill Bonemass?
The wiki lists two low-risk options. The first is to stand on top of his altar: climb it from the rear and use a two-handed club, whose slam reaches him and knocks minions off. You'll still get poisoned, so the mead stays mandatory.
The second is Frost arrows from high ground. Budget around 90 to 100 arrows, which means an early Mountain trip for Obsidian and Freeze Glands. A stone tower is safer than a tree, given what his punch does to wood.
How do you beat Bonemass solo or in a group?
Solo, use the plan above. You get the base 5,000 HP and all his attention, which makes the behind-him spot easier to hold.
In a group, each extra player within 100 meters adds 30% effective health and 4% damage, capped at five players (the wiki's Damage mechanics page gives 200 meters for the damage part). That's about 6,500 effective HP for two players and 11,000 for five. Assign your group's melee to minions first, since the cap of eight Skeletons and eight Blobs is the real threat. Bow users should spread out so that only one person has to run from him at a time.
What do you get for killing Bonemass?
- The Wishbone. Equip it, and it pings from about 20 meters away when you're near something buried: Silver in the Mountain, scrap piles in the Swamp, treasure in the Meadows and chests in the Deep North. It shares a slot with Megingjord and the Wisplight.
- His Forsaken Power. Hang the trophy at the Sacrificial Stones. It lasts 5 minutes on the shared 20-minute cooldown and covers allies within 10 meters.
- A hidden achievement. "Defeat the Writhing Dead" unlocks on the kill. Since achievements only track from 1.0, an Early Access kill doesn't count.
- World changes. Skeletons start spawning at night across the Meadows, Black Forest, Swamp, Mountain and Plains (0-star only). New raids unlock too, including "A skeleton surprise!" and "You are being hunted." Bat raids also become possible once a Bat has died, and those can wipe outdoor tamed animals, so roof in any prized boars before the fight.
Next up is the Mountain. Our Moder guide picks up from here, and the Wishbone is how you find the Silver for it.
Did patch 1.0.21 change Bonemass?
No. The 1.0.21 notes on Valheim's official site list no changes to Bonemass, Withered Bones or the Wishbone. A search of the Steam patch announcements back to Call to Arms found no fight changes either. His power's numbers appear in those Call to Arms notes as "25% resistance VS pierce, slash, and blunt damage, 100% reduced block stamina usage."
FAQ
What is Bonemass weak to in Valheim? Blunt and Frost, which each deal 150% damage. He takes 50% from Slash, 25% from Pierce and Fire, and nothing from Poison.
How many Withered Bones do you need to summon Bonemass? Ten, placed at his Forsaken Altar. Expect to mine about 12 Muddy Scrap Piles to find them, and you can reuse the altar if you collect 10 more.
Can you beat Bonemass without an Iron Mace? Yes. A quality 4 Bronze Mace needs about 82 hits at Clubs 30, close to an unupgraded Iron Mace. Frost arrows work too, at about 90 arrows.
Do Root Mask and Poison Resistance Mead stack? No. The strongest resistance overrides the others, so with the mead active the Root Mask gives no extra poison protection.
Can you use a bow on Bonemass? Yes, but bring Frost arrows. Pierce and Fire damage both drop to 25%, so a solo player with a maxed Huntsman Bow, Fire arrows and Bows 30 needs about 411 shots. A group can still whittle him down without Frost arrows.
What does Bonemass drop? His trophy and the Wishbone, which finds buried Silver, scrap piles, treasure and Deep North chests.
The bottom line
Bonemass is a damage-type check with a poison timer attached. Farm your bones and your iron on the same crypt runs, drink the mead before you summon him, and leave the Root Mask at home. Then bring a mace, stay behind him, and run the moment he leans back. Blunt damage does the rest.
More Valheim guides? Keep your run moving with our biome and boss coverage.
- Valheim Swamp guide: how to survive the Swamp
- Valheim boss order: all bosses and how to beat them
- How to beat Moder in Valheim
- Valheim armor tier list
- Valheim weapon tier list
Stats come from Valheim Wiki creature and item data, checked against Iron Gate's Patch 1.0.21 notes for Valheim 1.0.21 (2026-10-28). Hit, poison and armor tables are our own estimates. Values are base (0-star, single-player) and may change in future patches.
