Eater of Worlds

"A horrible chill goes down your spine..." "Screams echo around you..."

The Eater of Worlds is a giant Corruption-themed worm boss (resembling a Devourer, but much larger) with eyes on every segment of its body. It is summoned using the Worm Food from within The Corruption, or by destroying 3 Shadow Orbs.

The Eater of Worlds is not a single target, but a string of 50 segments (1 head, 48 body, 1 tail) with individual life counters. When any inner segment is destroyed, it splits into multiple smaller worms, each with their own head and tail. Each section of the Eater must be killed in order to defeat the entire boss.

Defeating the Eater of Worlds is the only way to obtain Shadow Scale, as well as usable quantities of Demonite Ore. Individual segments drop some of these when killed, with a larger bonus drop upon defeating the entire entity. The Eater of Worlds is immune to the Poisoned, On Fire!, and Cursed Inferno debuffs.

If your world generated Crimson instead of Corruption, this boss will be replaced by the Brain of Cthulhu.

Tips

 * Farming the Eater of Worlds is one of the most effective ways of making money prior to Hardmode. Mid-game armor and weapons will make the fight easy, and selling its drops will yield 9 to 11 each time, on average.
 * Weapons that pierce for multiple hits are effective, due to the Eater's large size (eg. Flails, Spears, Grenades, Spiky Balls, Molotov Cocktails, Vilethorn). The Harpoon is also effective, and is best used when being charged by its head.
 * The individual worms have a tendency to retreat into the ground when their heads are destroyed.
 * During Hardmode, it is an effective means of farming Soul of Night. One Soul of Night can be dropped per segment, the percentage being the same as with other mobs.
 * During Hardmode, the Eater can be summoned to heal yourself when your health is low, even while fighting other bosses: Your equipment at this stage will kill segments quickly, and each segment drops more than enough hearts to not only offset their negligible damage, but also heal your character significantly, if not fully.
 * Perhaps the easiest way to take care of the Eater of Worlds is using the Meteor Armor with the Space Gun. The Space Gun has high damage for this point in the game, and it pierces through enemies. Coupling this with the Meteor Armor's set bonus of the Space Gun using 0 Mana, you can easily pierce and kill multiple segments at once.
 * A faster but more expensive way to use Meteor gear is to use the Star Cannon. If the Eater comes for you from a direction not blocked by platforms or blocks you can kill the entire creature in as little as about 10 Fallen Stars, as they pierce infinitely and deal enough damage to kill a segment in as little as 2 hits.
 * If you are lucky enough to obtain a Water Bolt from the dungeon's upper section without having to fight Skeletron, it makes the boss battle trivial thanks to its piercing ability.
 * Vilethorn is a highly suggested weapon to use against the Eater of worlds. Considering you can find one by breaking shadow orbs which in turn will eventually spawn the Eater of Worlds only makes it more of a reason to use it. You can easily beat it in less than 3 minutes because of how the thorns hit multiple parts of it's body and it sticks around, making the Eater of Worlds move very slowly.
 * If possible, try to aim for the head or tails of each section, as if they die first, they will not split into more.
 * You should use fast swords like Phaseblade, Phasesaber, Muramasa,and Cutlass. The Muramasa is especially useful because of its constant damage. It is a recommended weapon against the Eater of Worlds
 * The Dark Lance is very effective when he is underground, as it kills each section allowing a player to stand in one spot.

History
Dévoreur de Mondes Eater of Worlds Пожиратель миров