Eater Of Worlds

Info
The Eater Of Worlds is the third easiest boss in Terraria and the Corruption equivalent of the Brain Of Cthulhu. It is a long burrower-type enemy with 67 (1 head, 1 tail, and 65 bodies) segments. If the body is split in two, it will subsequently make another, smaller, Eater of Worlds, and also making an extra head and tail. The head does extra damage and the tail extra defense, so doing this is not recommended, though sometimes it can be hard to help. The Hardmode equivalent of The Eater is The Destroyer, with lasers instead of Vile Spit and much more HP, attack, and defense. Also, the World Feeders and Devourers share a resemblance to The Eater.

To attack the player, The Eater will constantly burrow in and out of the ground, leaving its deadly body behind it like a trail. In Expert and Master modes, The Eater of Worlds will shoot Vile Spit from all sections of its body, including the head and tail. This vile spit inflicts the Weak debuff, which reduces your physical abilities. Beware, if you fight The Eater on the surface, he may cover the entire surface area of the corruption in his body, meaning you are unable to escape his grasp. If he does this, make sure you either have wooden platforms to seek refuge on, or have the Slimy Saddle so you can jump on him unharmed. Do not exit the corruption, as this will cause The Eater to burrow down into the ground until he despawns, and you will lose the chance to defeat him and gain his loot. That said, if you are not ready to fight him, exiting the corruption is not a bad idea.

In order to summon The Eater Of Worlds, you must smash three Shadow Orbs, which can be found deep in the Corrupted Caverns. The orbs can be smashed with any hammer, and as a bonus they have a 50% chance to cause a meteorite to fall. Alternatively, you can make worm food with 15 rotting chunks and 30 vile powder.

Strategies

 * If possible, always have a nearby house with a nurse and a dryad living there. The nurse can completely refill your health for a few silver coins, and the Dryad generates the 'Dryad's Blessing' buff which increases your defence. She also generates the Dryad's Bane debuff that negatively effects enemies, also make a long, flat arena, with heart lanterns, Campfires and Fireflies/Stars In Bottles.
 * Melee Weapons are recommended for the Eater Of Worlds, as ranged weapons have little effect on it and it takes way to long to defeat it with them. To use them best, run underneath The Eater's body while swinging to induce damage, just watch out for any incoming attacks from the head.
 * As said previously, make multiple wooden platforms you can stand on as to escape if The Eater covers the entire ground.
 * It is not recommended to fight The Eater underground. Instead, make a quick exit way for when you have smashed all three Shadow Orbs, or use Worm Food on the surface. If you do choose to fight The Eater underground, do not disregard the arena, though it may be tough to build it because the Demon Altars are in your way, and they cannot be destroyed until Hardmode.
 * Placing Spiky Balls from Goblin Invasions or bought from the Goblin Tinkerer on the ground will help drastically, as The Eater will continually take damage from them every time it burrows down or comes back up.

Achievements and Usefulness
Defeating The Eater Of Worlds earns you the Worm Fodder Achievement


 * The Eater Of Worlds drops Demonite Ore, which is incredibly useful as it can make the Nightmare Pickaxe, the earliest obtainable pickaxe that can mine Hellstone and Meteorite.