Swamp

The Swamp is where Valheim stops being gentle. Waterlogged, dark, and perpetually raining, it is the biome most runs stall on. The prize is iron, the metal that unlocks stone building and your next gear tier, and it is locked inside Sunken Crypts you can only open with the Swamp Key from The Elder. Everything here wants to poison you or drag you into the water, so you do not enter the Swamp without preparation. You enter it with a plan.

What lives here

Draugr and Draugr Elite are the backbone melee threat, hitting hard in groups. Blobs and Oozers spread poison on contact and in clouds. Leeches lurk in the water, which is why you stay on dry land and out of the murk wherever you can. Skeletons appear around crypts, Surtlings spawn near fire geysers, and Wraiths drift in at night. The water is as dangerous as the enemies: it slows you, hides Leeches, and turns a clean retreat into a drowning.

Never enter the Swamp without poison resist mead. Poison is the biome’s signature damage and it ignores most early defenses. Brew the mead at a Fermenter before you sail out, keep a stack on you, and re-drink it on cooldown during any extended fight.

What you gather

Iron is the headline. It comes from Muddy Scrap Piles inside the Sunken Crypts, dug out with a pickaxe and smelted from Scrap Iron. Iron unlocks the Stonecutter and stone building, an iron tier of tools and weapons, and the iron pickaxe. The crypts also hold Surtling Cores and Withered Bones. Out in the biome you gather Ancient Bark and Root for the Root armor set, Guck from glowing growths on trees, plus Blood Bags and Ooze. Collect 10 Withered Bones along the way: they summon the boss.

Remember the portal rule. You can portal the bones, bark, and guck home, but iron has to sail back by boat. Plan a crypt run as a haul-it-out-by-ship expedition.

Surviving the poison

The Swamp is a damage-type puzzle. Poison resist mead handles the biome’s worst attacks, but you also want the right weapon for the boss and the right footing for the fight. Keep to raised ground and the insides of crypts rather than wading. Dry off and re-eat at a forward campfire so you hold the Rested buff. Bring a mace: the metal here, iron, makes the iron mace that the boss is built around.

Beating Bonemass

Bonemass is summoned at its altar with 10 Withered Bones. It is a hulking mass of corpse and slime, and the fight is a test of damage types more than reflexes. Bonemass resists slash and pierce and shrugs off poison entirely, so swords and arrows barely scratch it. It is weak to blunt: an iron mace is the answer. Drink poison resist mead before and during the fight, because its poison cloud is otherwise lethal, and keep swinging blunt damage while you weave out of the cloud.

Killing Bonemass drops the Wishbone, which is progression-critical. Equipped, it pings nearby buried silver and treasure, and you need it to find the silver veins in the Mountains. Hang the Bonemass trophy on the Sacrificial Stones for its Forsaken Power: a 50 percent boost to physical resistance, the best defensive power in the game and a lifesaver in every later fight.

When to move on

You are ready for the Mountains when you have full iron gear, the iron mace, the Wishbone equipped, and frost resist mead brewed. The Mountains freeze you to death without frost protection, so do not set foot on a peak until that mead is in your bag or you have a cape that does the job.

Related: the Bonemass boss guide, the Black Forest behind you, and the full-run progression cheatsheet.