Eater of Worlds

The Eater of Worlds is one of the three pre-Hardmode bosses, It is similar in behavior to the Devourer, but has a lot more health and many more segments. It also splits into smaller worms as it takes damage. It appears to be made out of multiple Eaters of Souls that are linked to each other. If you destroy a segment that is neither head or tail, The Eater of Worlds splits at the spot that was destroyed and each half will continue fighting. However, upon splitting damage to each part remains; therefore, trying to maximize damage equally across the entire body will result in the most rapid kill.

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The Eater of Worlds is either summoned in The Corruption with Worm Food, which is made out of 15 Rotten Chunks and 30 Vile Powder or by destroying three Shadow Orbs. Either method may be repeated. Since patch 1.0.5, the Eater of Worlds can only be fought in the Corruption. Attempting to leave the Corruption will cause the Eater of Worlds to flee in a few seconds. (Prior to patch 1.0.6, the player would get the message "Eater of Worlds was defeated." instead of "Eater of Worlds flees.") There need to be at least 500 Ebonstone blocks nearby in order to be considered inside a valid Corruption area.

The Eater of Worlds drops Coins, Demonite Ore and Shadow Scales upon the death of each of its segments. These are used to create Shadowscale Armor, as well as Demonite-tier tools such as a Nightmare Pickaxe or The Breaker.

Strategy
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 120hp and 0 defense, the body segments have 200hp and 2 defense, and the tail has 300hp 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 53 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, Ball O Hurt (both of which are dropped from Shadow Orbs), and a bow (preferably a Golden Bow or better) with Unholy Arrows (which can be crafted from the Worm Teeth that Devourers drop), though a Golden Broadsword or better can be used if none of these are available. Silver Armor or better is recommended, as well as having at least 200 HP. 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 well over 6000!


 * 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 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.

Weapons Analysis

 * Vilethorn: This weapon does only 8 damage (7 to the body segments), but it's here due to how it can hit enemies multiple 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 though, 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.


 * Terraria_Eater_of_Worlds_Massacred.jpgon : 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.
 * Ball O Hurt: A neat little trick that you can do with this weapon, since patch 1.0.6 came out, 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.


 * Bow with Unholy Arrows: A Gold Bow with Unholy Arrows will do about 19 damage, while a Demon Bow with Unholy Arrows 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%.
 * A simple broadsword so when he is making a cresent shape around your body go to one side and spam it it will most likely hit 3-2 times on one segment each with the right timing.

Arena
Since this boss can only be fought in the Corruption, your arena will need to either be located in the Corruption, or be made out of enough Dirt Blocks covered with corrupted grass and/or Ebonstone Blocks (500 blocks should do the trick) for the game to determine that it lies within a valid corrupted area. The arena doesn't have to be very big (around 75 blocks is a nice width), though it should have a roughly flat surface at the bottom, and at least 2 rows of wooden platforms for avoiding the Eater of Worlds should it decide to swim along the surface of the bottom floor, or one of the rows of wooden platforms. If you'd like, you can dig some holes beneath your arena (and to the sides and above it if it was built underground) to more easily spot the Eater of Worlds before it attacks.

If you built your arena above ground, then you may have to deal with it becoming tangled up more often, as the boss doesn't have much earth to swim around in. However, if you built your arena partially or even fully underground, then the boss shouldn't tangle up as much, and can easily be set up for a quick kill (as mentioned before), though you will have to keep an eye on every side of your screen, as the boss can burst from the walls, or (if deep enough underground) even the ceiling.

Bugs

 * There is a bug where there can be 2, 3, or even more eater of worlds out at once if you use worm bait, then break 3 or more shadow orbs (3, 6 ,9, etc.) . Although, when you die, all but one of the eaters go away.
 * A few players have come across a bug where they defeated the Eater of Worlds after they took away most of his body parts but then died. The players got all the items and coins he supposedly dropped though. Most of the claims could be confusion however, as defeated segments do drop some loot (including Demonite Ore and Shadow Scales) as the battle goes on.
 * Another rare bug is that the boss will spawn as only a single segment, and nothing else. It will function the same as normal, just very ineffective at killing anyone.
 * One very specific bug may happen if the Eater of Worlds is fought in the Underground Jungle. Some of its segments may get "chained/fused" with a Man Eater and stand still.
 * Another bug is that the boss will be summoned on world creation (i.e. Make a world then enter it.). This is most likely caused by deafeating a boss and then immediatley creating the new world.
 * Another possible bug is when you've cut the Eater of Worlds into several segments and one kills you, that worm will disappear but the others will continue to fight. (needs confirmation.)