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Valheim boss fight guide: Bonemass tips

Bonemass strategy is all about preparation

Valheim’s Bonemass boss running through the swamps Image: Iron Gate Studio/Coffee Stain Publishing via Polygon
Austen Goslin (he/him) is an entertainment editor. He writes about the latest TV shows and movies, and particularly loves all things horror.

Getting your base started in Valheim is the first big hurdle, but once you’re rolling along comfortably, you can start taking on the game’s bosses. While the first two bosses aren’t necessarily easy, it’s not until the third boss, Bonemass, that things really get challenging.

Unlike Eikthyr and The Elder, Bonemass requires quite a bit of special preparation and knowledge, so in this Valheim Bonemass guide what kind of gear you’ll need to do it.

Table of contents

Preparing for Bonemass
Bonemass strategy
Bonemass trophy and rewards

Preparing for Bonemass

You or your group will be ready to fight Bonemass after you’ve spent some time collecting iron and crafting iron gear.

Since iron comes from the swamps, it’s likely that somewhere along the way you’ll find Bonemass’ summoning location, which you’ll need to know before the fight. Once you know where he is, you’ll need to make sure you have the right gear prepared before you summon him for the fight.

Bonemass’ summoning skull in Valheim Image: Iron Gate Studio/Coffee Stain Publishing via Polygon


Bladed and piercing weapons won’t do much damage to Bonemass. Instead, you’ll need to craft a blunt weapon like a mace — preferably iron, but bronze can work, too.

Similarly, bows won’t work well against him, but you should bring them along for reasons we’ll get into later.

At least one person in your party should also bring a Stagbreaker hammer to help clear smaller enemies during the fight. If you’re alone, it makes for a good backup weapon.


Armor is slightly less important for Bonemass game because most of his damage comes from poison, rather than direct hits. You can make a full suit of iron armor, but bronze or even troll hide would likely be fine.

Rather than great armor, you’ll instead need to bring plenty of strong food with you. Meat-based food gives you the most health, which is exactly what you’ll need when fighting Bonemass. Your best food options will be sausages, cooked meat, and turnip stew or cooked lox meat, if you’re brave enough to venture into the plains to find it. If you can’t get three meat-based foods, Queen’s Jam is a good substitute.


The Poison Potion recipe in Valheim Image: Iron Gate Studio/Coffee Stain Publishing via Polygon

The final step to preparing for Bonemass is having poison resistance potions to mitigate his damage. Poison resistance potions require honey, thistle, neck tails, and coal. You have to be bake them in a cauldron and then brew them in a fermenter. They take a very long time to brew so get started on this early.

Each potion lasts 10 minutes, and they’ll need to be active for the entire boss fight, so you’ll probably need more than one. Two potions should get you through the fight, but everyone in your group should bring three, in case something goes wrong and the fight takes a very long time.

Bonemass strategy

Bonemass’ location is always in swamps, which means there are enemies everywhere and some pretty deep and dangerous water, so be careful where you fight him. Clear out other enemies in the area before you start your fight with Bonemass.

His summoning location usually involves a lot of dry land. Keep him close to that, so you avoid the swampy, leech-filled waters.

Once you clear the area and figure out where to fight him, head to the giant skull and summon Bonemass by adding 10 withered bones to the boiling green liquid in the giant skull.

Bonemass attacks

Bonemass has three attacks to learn and recognize.

  1. A slow swipe to his front with his right hand. Getting hit by this will deal heavy damage and poison you, but it’s pretty predictable and slow, making it easy to dodge.
  2. Bonemass pulls slime off of his body and throws to make blobs that join the fight against you. This animation is very long and can’t hurt you, so get several hits in during it. Kill the blobs that spawn quickly, ensuring that they don’t overrun you later in the fight.
  3. Bonemass rocks forward and backward and unleashes poison all around himself. This area-of-effect poison ability is also slow but it hits hard, so don’t get too greedy while he’s casting it.
The Bonemass boss in Valheim Image: Iron Gate Studio/Coffee Stain Publishing via Polygon

Attacking Bonemass’ weaknesses

Bonemass has a lot of health, so this will mostly be a war of attrition. Take things slowly, and don’t get too close if you don’t have enough health to survive. You’ll need more health than you might think because you have to survive the ticks of poison as well as the initial hit.

When you need to fall back, use your bow to damage Bonemass. Otherwise he’ll slowly heal himself when he stops taking damage for too long. Your bow is also a great tool for pulling him out of his own AOE poison clouds. Other than these two uses, the bow does almost no damage, so limit its uses to these situations only.

Bonemass trophy and rewards

After the very long and slow fight, you’ll eventually take Bonemass down. Once he dies, he’ll drop the Bonemass trophy, which you can use at the summoning circle for a new resistance power. Every player in the party also gets a wishbone, which lets you know when there’s silver nearby.

Now that you’ve conquered the swamp, you can head into the mountains in search of silver and wolf pelts.