Calamity Mod Wiki
Calamity Mod Wiki
Ark of the Cosmos
  • Ark of the Cosmos.png
Stack digit 1.png
Damage501 Melee
Knockback9.5 (Extremely Strong)
Critical chance19%
Use time14 Very Fast
TooltipFires different homing projectiles based on what biome you're in
Upon hitting an enemy you are granted a buff based on what biome you're in
Projectiles also change based on moon events
RarityRarity Level: 15
Sell 50 Gold Coin.png
Projectiles created
Eon Beam (All)
Eon Beams
Galaxian Star
Galaxian Star

The Ark of the Cosmos being used against a Target Dummy and a more distant Super Dummy.

The Ark of the Cosmos is a craftable post-Moon Lord broadsword that autoswings. It is the final upgrade of the Ark of the Ancients and Biome Blade. It fires a tile-ignoring and enemy-piercing beam sword of one of four colors when swung. In addition, it rains homing, tile-ignoring stars towards the cursor. The blue and orange sword beams inflict the Elemental Mix debuffs onto enemies, while the green and pink beams only inflict the Holy Flames debuff.

Upon any of its projectiles hitting an enemy, a projectile is spawned and the player receives a buff. This is dependent on the biome the player is in. The moon events will also grant different buffs to the player when they are active. All buffs last 10 seconds.

  • Otherwise, (e.g. in the Abyss/Forest) it will grant the Dryad's Blessing buff and the Ark of the Cosmos will fire the orbs from the Terrarian.
    • The same effect occurs when the player is in a non-Calamity modded biome.

In addition to this, the sword inflicts the same debuffs as its predecessors based on the biome the player is in for 20 seconds.

Its best modifier is Legendary.


For a full crafting tree, see here.



  • If the player travels into a different biome after a projectile is fired, the projectile's effect will change to the new biome.


  • Ark of the Cosmos is useful against enemies who have high mobility or keep a safe distance away from the player as it shoots lots of high-damage, homing projectiles.


  • The base damage of the Ark of the Cosmos is the sum of the base damages of the Galaxia and Ark of the Elements.