A Guide to Bonemass -Valheim

In Valheim there are a set of elder creatures which must be slain and sacrificed to the gods. These are Odin’s greatest enemies and the reason you were brought to Valheim upon your death on your home planet. The third and most disgusting boss you will reach will be known as Bonemass. Upon defeating The Elder, you will technically be given all you need to defeat Bonemass.

Bonemass is how it sounds. It is a huge green blob consisting of bones meat and other discarded parts. The mass lives in The swamp and its main attacks consist of summoning other slimes to help it with the battle and poison based damage. If you are a solo player you are going to have a hard time beating Bonemass, though nothing is impossible with the right strategy.

You can check out our guide to the first boss Eikthyr and a guide to the second boss, The Elder, here.


You can click any of the headings below to skip straight to a relevant part of the page.

Finding Bonemass

Summoning Bonemass in Valheim
Cook Their Remains
Getting Withered Bones
Using The Boiling Death

Fighting Bonemass
Bonemass’ Attack Set
Fighting Tactics

Bonemass Trophy

How to Find Bonemass

Finding the location of Bonemass is done in the same way as finding the other bosses of Valheim. You must find the correct Vegvisir to mark the location of Bonemass. This Runestone won’t be located on the surface or Valheim so you will have to go underground and do a bit of spelunking to uncover Bonemass’ location. The runestone to mark the location of Bonemass will be found underground in the Sunken Crypts. You will have to defeat the second boss, The Elder, in order to get the Swamp Key which will be the only way you can get into the Crypts in the swamp.

Opening a sunken crypt in Valheim with the swamp key
Exploring crypts in the swamp is your first step to finding Bonemass

Once inside the swamp biome, look for the green bright torches that will guide you towards the sunken crypt. You will see that the entrance to the crypt is closed and you will not be able to get inside. As long as you have defeated The Elder and have a Swamp Key in your inventory you will be able to unlock the gate. Once a crypt gate is unlocked it will remain opened forever. You will only need to bring one swamp key for the whole party and the Swamp Key can be reused as many times as you would like so don’t worry about ‘picking the right crypt’.

Find the Vegvisir Bonemass

Once you have entered the sunken crypts you should be relatively safe. You will notice straight away that many paths may be blocked off or that you cannot go very deep into the crypts. You will see that there is muddy scrap piles covering the doorways. These muddy scrap piles can be mined with a pickaxe to reveal a deeper cave. Mining out these muddy scrap piles will be the way that you get Iron in the game so it isn’t just a case of finding Bonemass, you’ll also be collecting helpful iron.

Iron scraps, Withered Bone and Leather scraps will drop from mined muddy scrap. All pickaxed can mine muddy scrap including the first pickaxe in the game which you will be able to craft after defeating Eikthyr.

Mine muddy scrap piles in valheim to get leather scraps and iron scrap

Finding the Vegvisir to unlock the Bonemass’ location will be random. It could be in the first crypt that you enter or it could be in the 10th. Personally, I found the location marker after my 4th crypt. It isn’t the worst thing if you can’t find the location straight away. Mining scrap piles is your ticket to collecting a good amount of Iron. Iron will be very helpful in fighting Bonemass, believe me! You are going to want to gather as much iron as you can before the coming battle.

Interact with the Bonemass Vegvisir to mark the location of Bonemass on your map

Once you find the Vegvisir to mark Bonemass’ location, interact with the ‘E’ key by default. A marker will then be placed on your map showing you the area where Bonemass can be summoned from.

How to Summon Bonemass

Once you find your way to the point on the map marked for Bonemass you will see the altar. Bonemass can be summoned from the large stone skull in the swamp. You will see that the mouth for the skull is opened and there is poison material bubbling inside.

This works exactly the same way as the other altars up to this point and summoning Bonemass is merely a case of having the right amount of a certain material and offering it up to the altar.

Cook Their remains

Cook Their Remains is the clue given at the Boiling Death altar. You can find this runestone at the back of the boiling death altar. The Runestone may be in the water so as always in the swamp remember to look out for leeches when trying to navigate through the areas. Cook Their Remains, refers to the Withered Bones you may have seen around in the Crypts.

To summon Bonemass, you will have to find 10 Withered Bone and offer it into the Boiling Death pit.

Burn Their Remains clue for bonemass in Valheim
Cook Their Remains is the third cryptic clue in Valheim

How to Get Withered Bone

Withered Bone in-game description in Valheim. A giant bone, knotted life old wood.

The in-game description for Withered Bone reads ‘A giant bone, knotted like old wood.’

There are a few different methods of gathering Withered Bone. Finding 10 Withered Bone is a relatively easy task compared to the gathering of Ancient Seeds you had to do for The Elder. You can find Withere Bone scattered randomly in the Sunken Crypts that you were exploring in order to find the location of Bonemass. Here, at the ends of hallways you will sometimes find a Withered Bone.

You can also find Withered Bone on the surface in the swamps. There will be some randomly generated structures around the swamps like small towers and buildings. These buildings will generally be guarded by skeletons or Draugrs so watch out for them! These buildings will have a chest will loot inside of them. Fairly often you can obtain a Withered Bone from these loot chests in the swamp.

Using The Boiling Death Altar

Once you have gathered 10 Withered Bone it’s time to head back to the Boiling Death altar. From this point you must make sure you are ready for the fight ahead. There is no going back at this point so make sure you’ve got all of your affairs in order. If you do manage to be slain by the Bonemass in the battle, Bonemass will not despawn so you will not have to find 10 more Withered bone.

The boiling death. Bonemass summoning altar in valheim

Equip the Withered Bone into one of the numbered quick bar slots and press the corresponding number when facing Boiling Death.

This will consume your 10 Withered Bone and summon Bonemass, the third boss of Valheim

How to Fight Bonemass

Fighting Bonemass straight off the bat is going to be a tough task. Bonemass is resistant to many different types of damage. Bonemass is very resistant to Piercing and Slash damage to most weapon types will be pretty useless in this fight, or simply take too long to be even worth using.

Bonemass is a large green slime creature who moves across the ground. Bonemass cannot move through the trees in the swamp. Bonemass can move through the water with ease. Although Bonemass is a difficult fight, it has a lower health pool than the Elder.

Bonemass’ Attack Set

Bonemass is a land based character who moves by sliding around the ground and through water. Bonemass uses poison based damage to do damage over time to the unprepared player. Poison damage is hard to dodge and once the player is damaged they will have to wait until the poison is over. Water will not alleviate the player from their poison ailment. Bonemass has 3 attacks at its disposal, once of which is used to spawn Blobs to help Bonemass fight and the other 2 attacks are to damage the player.

This is a similar attack move set to The Elder.

Attack 1 – Melee Swipe Attack

If Bonemass manages to get close to the player it will attempt to use one of 2 different attacks. The first attack we will discuss is the melee swipe attack. Bonemass will reach back and swipe the player in front of it. Bonemass will use it’s right arm to swipe and the hitbox will range from the right side of Bonemass to the front. This attack can be blocked but does a great deal of damage so a banded iron tower shield would be recommended to try to tank the boss.

The bonemass fighting using it's melee attack

The player can also dodge the attack by rolling out of the way. Timing the roll at the right moment would allow the player to take no damage whatsoever from this attack.

Attack 2 – Poison Spew Attack

Bonemass has another attack that they will attempt to use within melee range. For this attack, Bonemass will charge up and spew poison in a forward facing direction towards the player. This poison damage can’t be blocked as if the player stands still the poison will cover them completely. The attack doesn’t do any direct damage itself but will leave the player at the mercy of a devastating poison.

Bonemass will spit poison over the player in Valheim

It is recommended to dodge-roll away from this one if you see Bonemass getting ready to spread it’s poisonous bowels across the swamp.

Attack 3 – Ranged Blob Spawn

Bonemass’ third and final move is one that doesn’t deal any direct damage to the player. Bonemass will spawn 3 blobs to help it fights the player from time to time. The blobs have a similar damage structure to Bonemass where many different types of damage are not so effective. A good way of dealing with the Blobs is by doing large amounts of blunt damage. The Iron Mace is the best recommended weapon for this one.

Bonemass will throw 3 Blobs to help them fight in Valheim

Bonemass will generally throw the blobs over the players head in an attempt to flank the player. You should try to deal with the Blobs as soon as possible as they can easily overwhelm the player.

Tactics/Methods of Fighting Bonemass | How to Beat Bonemass

Bonemass can only move across the land. You can use the unbreakable large trees in the swamp to your advantage in the fight. If you can trap him somewhere you can pretty easily beat this fight. As aforementioned Bonemass has resistances to almost all damage types in the game. Piercing and Slashing damage will do next to nothing to Bonemass. Bonemass is very weak against Blunt damage however. The player could use a weapon such as the Iron Mace, or a Sledgehammer to defeat Bonemass.

Using an Iron Mace which had been upgraded once, I was able to do 50-70 damage per regular swing, with the end of the combo doing around 120 damage.

Bonemass can be set on fire but will take very little damage. Each tick of fire damage from a torch will do 0.5 damage to Bonemass.

Some preparation will be key before you tackle Bonemass. Before you spawn this creature first of all set up a base, somewhere nearby in a relatively safe area. That way when a member of the tribe falls they will be able to come back to the fight easily. Mine as much Iron as you can and use it to create some decent armor and an Iron Mace. Blunt weapons are really the best thing to use here. It is recommended to go through the swamp and clear all the enemies around first. The fight may go over a large distance throughout the swamp and any Draugrs, Skeletons or other enemies will join the fight for the Bonemass.

When Bonemass spawns new Blobs behind you, take your time to clear them out first. Getting overwhelmed by many smaller enemies will be your greatest threat here. The Blobs can be killed fairly easily with one or two hits from an Iron Mace.

Consider creating some Poison Resistance Mead if you have a fermenter and cauldron. This will make the poison last for half the amount of time and not do as much damage to the drinker.

If you have multiple Vikings at the battle, take turns tanking Bonemass. While one character is taking the attention of Bonemass have everyone else attack it. If a player gets low health you can easily outrun Bonemass and go heal up while the others keep its attention. Even if you just have a bow with fire arrows you will still be able to do a little damage. So if you don’t have enough Iron to go around, have one character build decent armor and an Iron Mace. Everyone else can still use fire arrows to whittle Bonemass’ health down slowly but surely, (and safely!)

Bonemass is going to be a long fight but utilizing its blunt damage weakness, keeping the extra enemy spawns at bay and staying out of the poison will be the key here.

Loot Dropped By Bonemass

Congratulation of defeating Bonemass! You’re one step closer to Odin’s revenge on his greatest enemies. You’ve defeated the third boss on your journey in Valheim. You will be given two items of loot upon successfully defeating Bonemass. Bonemass can be defeated multiple times to get the loot again.

Bonemass Trophy

Bonemass trophy on the sacrificial Stones to give forsaken power valheim

The Bonemass Trophy will drop every time that Bonemass is defeated. You can attack this trophy to the corresponding sacrificial stone where you first started your adventure. Attaching the trophy to the stone will allow you and other players on the server to interact with it and gain the forsaken power of Bonemass.

Bonemass’ forsaken power will make the user more resistant to all types of physical damage. This includes greater resistance to piercing, slashing and also blunt damage, (even through Bonemass was weak against blunt damage). This will not reduce the harmful effects of poison, drowning, freezing or burning damage.

The Forsaken power of Bonemass will make the player more resistant to physical damage when used


The in-game description for the Wishbone reads; This ancient bone remembers the location of many forgotten things.

The other item that will be received from Bonemass is the Wishbone. This item can be used to find ‘hidden objects’. The in-game description for the Wishbone reads ‘This ancient bone remembers the location of many forgotten things’.

Once the player receives the Wishbone, Hugin the raven will appear and give the player advice on how to use it. Hugin says, ‘Bonemass left you a parting gift. It seems one of the many bones this living ossuary hid in his belly was a Wishbone. This bone contains powerful magic that guides you to things hidden in the Earth. It can locate Silver veins, but may also lead you to buried trasure…

If the players can both a belt item and the Wishbone they may only equip one at a time. Equipping and using the Wishbone will force the player to remove the Megingjord.

Hugin the raven giving helpful advice to the player in Valheim

I hope this guide on Bonemass has helped you slay him. What’s next? Stay tuned for the next guide as we face up against the fourth boss in Valheim.

Related: How to Get Copper in Valheim | How to Get Fine Wood in Valheim