The Bonemass boss (simply called Bonemass) is the third boss in Valheim and appears as a vast humanoid blob mixed with many bones within it.
After defeating Bonemass, you will be able to progress into finding more Iron and discover how to farm Silver Ore from Silver Veins in the Mountains biome.
After collecting the summoning items needed to make Bonemass appear, you will have to place them in a giant skull full of goo labeled “Boiling Death.”
In this Bonemass guide, we will show you everything you need to know about Bonemass summon requirements, how to defeat it, and some tips that will be useful in the fight.
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Bonemass Altar Location
You can discover the location of the Bonemass offering shrine by going into the Sunken Crypts and mining your way around the area.
It may take a bit of time because not all of the Sunken Crypts will reveal the location since you will need to find the Vegsivir Bonemass stone.
Once you find Bonemass’ Vegsivir, interact with it, and the Bonemass offering location will be revealed on your map.
How to Summon Bonemass?
To summon Bonemass, you will need to bring 10x Withered Bone to the Boiling Death offering structure, which is located in the Swamp biome.
If you have found Bonemass’ Vegsivir, you will be able to easily find its location and can begin summoning it as long as you have the Withered Bones with you.
Once you summon Bonemass, the area will turn to a darkish glow, and you will be attacked by Bonemass along with the enemies that it spawns.
Bonemass is very large and can cause a lot of poison damage if you get reckless, so be sure to keep your distance and parry or block any attacks if he gets close to you.
Sometimes Bonemass will start regurgitating and will spit out poison in an area around him which can cause you to become poisoned and take damage over time.
If you are near Bonemass, it will attempt to take a massive swing at you, and you must dodge or block this attack, or you will end up suffering from heavy damage.
From time to time, Bonemass will reach into its armpit and throw a blob at you or near you, which will spawn Blobs and Skeletons.
When fighting Bonemass, it is essential that you use Poison Resistance Mead, or else you can die easily from the poison damage it or the other Blobs may cause.
For a guide on making Poison Resistance Mead, check out our Valheim Potions Guide.
Bonemass is weak against blunt damage, making the Iron Mace the best option for you during this phase in Valheim.
If you happen to venture out into the Mountains biome, you may have encountered Drakes, which drop Freeze Glands that you can use to make Frost Arrows.
Frost Arrows are the only arrows in Valheim that can deal a good sum of damage to Bonemass as the others are weak and will not be helpful.
It is best to parry his attacks while attacking him with your blunt weapon but staying at melee range requires that you be careful.
As you will be facing several enemies, you should also bring an Iron Sledgehammer or a Stagbreaker to easily deal damage in an area to clear them out.
It is possible for you to stay on one of the indestructible Ancient Trees in the area, and you can build structures going up or find a fallen one to stay away from Bonemass and the other enemies.
From high ground, you can effortlessly fire Frost Arrows at Bonemass until it is defeated, making it an easy fight.
You may need to farm a good amount of Freeze Glands to craft a bunch of Frost Arrows, but this will be worth it later on.
For a guide on Freeze Gland farming, check out our Valheim Freeze Gland Farming Guide.
How to Get Withered Bone?
You will need to collect 10x Withered Bones to summon Bonemass, and these can be found mostly in the Sunken Crypts by mining Muddy Scrap Piles.
It is possible to dig up Withered Bone from Muddy Scrap Piles in the Swamp biomes, but it will be hard to find without a Wishbone.
Once you have collected 10x Withered Bones, these are brought to the Boiling Death summoning altar to spawn Bonemass.
Upon defeating Bonemass, it will drop a Wishbone for each player, which is useful for larger groups who will want one.
Like all bosses in Valheim, Bonemass also drops the Bonemass Trophy when it is killed, which you can place on its respective altar to unlock its Forsaken Power.
It is also worth mentioning that the enemies spawned by Bonemass will have loot dropped when they killed, making it easy for you to farm items dropped by Skeletons and Blobs.
After unlocking Bonemass’ Forsaken Power, you will be able to use it to provide you with increased resistance against physical damage.
This includes blunt, pierce and slash damage, making it excellent for going into battles to improve survivability for 5 minutes.
Bonemass is a poison-based enemy, and it will most likely poison you often if you attempt to fight it at close range.
It is vital that you prepare Poison Resistance Mead to reduce the damage you take from the poison it inflicts you with.
While blunt weapons deal the best damage against Bonemass, Frost Arrows are a good alternative and make Bonemass solo fights easy.
The Bonemass fight is one of the hardest fights in the game due to the poison damage, enemies that can attack you in the Swamp, and the constant spawning of Skeletons and Blobs.