Disclaimer: For the purposes of this guide, it is assumed that the player is using a new character in a new world, and would therefore not have access to late-game equipment, such as Molten Armor, a Fiery Greatsword, a Star Cannon, etc. Otherwise, this boss would be a piece of cake.

To defeat this boss, one must destroy every individual segment that makes up its body. The head has 65 and 0 defense, the body segments have 150 and 2 defense, and the tail has 220 and 4 defense. Each section must have a minimum of two body parts (a head and a tail). If either of those parts reach 0 health and there is no body segment to replace it, then both parts die. The Eater of Worlds begins with 50 segments.

Since this boss is composed of multiple segments that each have their own HP, weapons that can hit multiple enemies per attack are recommended. These include the Vilethorn, any kind of flail (such as the Ball O' Hurt) and a bow (preferably a Golden Bow or better) with Unholy Arrows, though a Gold Broadsword or better can be used if none of these are available. The Harpoon is also highly useful against this boss, since it's more than capable of striking multiple segments on his body at once if the player stands close enough.

• Vilethorn: This weapon does only 8 damage (7 to the body segments), but it's here due to how it can hit multiple enemies several times per attack, so this damage can really add up fast. Moreover, this weapon passes through solid blocks, so it can damage the Eater of Worlds even when it's underground. It uses up 12 mana per use, so you should consider using a different weapon if your max mana is low. The Magic Power Potion will increase the power of this weapon by 20% for 2 minutes.
  • How-to-get: Smash Shadow Orbs.

• Harpoon: Very effective in short range against the Eater of Worlds. It does 25 damage and can fire almost as fast as the Minishark in close range, thus making it a very effective weapon against the Eater of Worlds.
  • How-to-get: Drop from Goblin Army.

• Ball O' Hurt: A neat little trick that you can do with this weapon (as of patch 1.0.6) is that you can toss the ball out, keep it held out by holding down the left mouse button, and it'll damage enemies even when the ball is not moving around. If the Eater of Worlds passes through this, then whatever segments touch this will take continuous damage, which will add up even quicker than what a Vilethorn can dish out.
  • How-to-get: Smash Shadow Orbs.

• Bow with Unholy Arrows: A Gold Bow with Unholy Arrows will do about 19 damage, while a Demon Bow will do about 22 damage. The best time to use this weapon effectively is when the Eater of Worlds is swimming horizontally along the ground (as seen in the picture to the right), allowing you to damage not only the head, but quite a few segments as well. Archery Potions can be used to increase the damage done by 20%.
  • Crafting: Arrows are crafted with the Worm Teeth that Devourers drop

Silver Armor or better is recommended, as well as having at least 200 . Bring along a few (Lesser) Healing Potions as well, as the head deals a massive 40 damage (minus armor), though the body segments deal only 15 damage by comparison.

The following optional Consumables may also be of some use during this boss battle, if you're willing to use them that is:

• Ironskin Potion: Increases your defense by 8 for 5 minutes, allowing you to take 4 points less damage from attacks. Although you should still avoid the head at all costs, it'll at least make the damage inflicted by the body segments less painful.

• Thorns Potion: For 2 minutes, enemies that attack you take damage equal to half of the damage that was inflicted upon you. Although this can make the fight go by a bit quicker, you have to take damage for the potion to work. Although many people would rather prefer to not get hurt by the boss's attacks, only using this in case they do get hurt, if you REALLY wanted to use this as a major source of damage, then you're going to have to use up quite a few Healing Potions (and maybe a few Regeneration Potions as well) to keep yourself alive, as the total HP of all of the segments combined is a little over 7000! (7485 total base HP.)

• Regeneration Potion: For 2 minutes, your health regeneration is increased. Like the Ironskin Potion, this can also make surviving the Eater of Worlds' attacks a bit easier.

• Archery Potion: For 4 minutes, your bow deals 20% extra damage. Works well with a bow loaded with Unholy Arrows.

• Magic Power Potion: For 2 minutes, your magic attacks deal 20% extra damage. Works well with the Vilethorn.

• Hunter Potion: For 5 minutes, enemies, including the Eater of Worlds, glow. This can make avoiding the Eater of Worlds's attacks easier, as players can even spot it while it's burrowing underground.

Because the head deals so much damage, it is strongly recommended that you avoid it at all costs, even if it means having to move through the boss's body segments (taking damage in the process). Also, it may be a good idea to aim for the head, as not only does it have less defense and HP than a body segment, but splitting the boss up by destroying body segments will only make it more difficult to dodge its attacks. (Focusing on the head should also increase the amount of loot dropped.) When the head is destroyed, the boss will stall for a bit, allowing you to take aim and fire at the new head. If the player is using one of the above recommended weapons, then it is possible for the player to stall the boss this way almost indefinitely, leading to a quick, easy kill.

It is ill advised to fight the Eater of Worlds inside a chasm, as not only can it strike with little warning, but it could also knock you to your death. You could use the Grappling Hook to cling onto a wall, though you should still avoid getting struck by the head as, again, it deals heavy damage to players.