Eye of Cthulhu

The  is one of the Pre-Hard Mode bosses in Terraria. It is usually the first boss that new players encounter, and is generally considered to be the easiest boss in the game.



Summoning
The (often abbreviated as EoC) can be summoned by using a Suspicious Looking Eye at night. Alternatively, it can randomly spawn with a 33% chance each night if the following criteria are met: If these conditions are met, the player may get the message, "You feel an evil presence watching you...", which means that the Eye will spawn soon. After about 15-30 seconds the message, "The has awoken!" will appear and the boss will promptly start to attack the player. However, if the player isn't ready to fight the, the battle can be cancelled by simply exiting and restarting the world, or alternatively restarting the game.
 * At least one player in the world has at least 200+ HP.
 * There are at least four NPCs in the world. Note that the Old Man counts as one of these.
 * The has not already been defeated in the world.

Strategy
The has two phases that it goes through as it does battle with the player. The first phase, a giant eye, has 15 attack power and 12 defense, while the second phase, a giant eye with a gaping jaw in place of its lens, has a 23 attack power; however, it has no defense. A good weapon to use during the first phase is the Starfury: It being a broadsword means you are able to fend off The Servants Of Cthulhu and use its ranged ability to fight Cthulhu. Another weapon suggestion for the first phase would be the Space Gun. (It is advised that the player has full Meteor Armor as this makes the Space Gun use 0 Mana.) The Crimson Rod can also be useful when the Eye is simply hovering, as it will kill the Servants easily and allow the player to focus on the Eye. It can also deal a good bit of damage when the Eye is switching phases as it will stay stationary when doing so.

Preparations
As the can only summon itself if your max HP is 200 or more, you can delay its arrival by holding onto any Life Crystals that will increase your max HP to 200 or more until you feel that you're ready. That way, you'll be able to wait until you can craft Gold Armor and a Gold Bow. However, if you're not patient enough to want to grind for gold-tier equipment, then you should at least have Iron Armor or better, an Iron Broadsword or better, and, most importantly, some sort of ranged weapon, such as Shuriken, Throwing Knives, or a bow (preferably Iron or stronger) with Flaming Arrows. Also, bring along any Lesser Healing Potions in case you need to heal. If possible, get Glowing Mushrooms for Healing Potions instead.

If you are feeling like just rushing in the game, and are skillful or lucky enough, you can make a Topaz Staff, get some Fallen Stars for extra mana, and get some Iron Armor. With 160 or 200 health, and Healing potions, you can beat the eye with just dodging skills and a nice aim.

The following consumables may also be of some help:
 * Ironskin Potion: This will increase your defense by 8 for five minutes, allowing you to take up to four less damage from the 's attacks.
 * Thorns Potion: For two minutes, enemies will take half of the damage that you take. This can make the battle go a bit quicker, though you'll probably want to try to avoid the Eye's attacks instead, especially during phase two.
 * Archery Potion: For four minutes, the damage dealt by your bow & arrow increases by 20%, which will help decrease the time of the battle greatly.
 * Regeneration Potion: For two minutes, your health regeneration is augmented, allowing you to recover more lost health in a faster period of time.
 * If you have explored enough, and you are better with melee weapons in general, a Gravitation Potion with a silver or golden Broadsword may also be of use.
 * A Mana Potion may be of use if you have magic items such as crimson rod or aqua scepter, (If you have found it in a chest or a friend has gifted you it.

Weapons Analysis

 * Shurikens: These weapons can be thrown rapidly and can penetrate through enemies, meaning that these can not only kill Servants of Cthulhu in one hit (thanks to their attack power of 10), but they'll also go on to damage the Eye itself. Although they only deal 4 damage to the Eye's 1st phase, due to their piercing mechanics, they'll often damage the Eye more than once, making them an ideal weapon. They're pretty easy to obtain as well, since not only are they commonly found in pots, but they can be purchased from the Merchant at any time for only 20 copper each. Throwing them straight in the iris of the Eye will hurt the servants as well.
 * Throwing Knives: Although they are a bit harder to get than Shurikens (they're also common in pots, though the Merchant will also sell them during a Blood Moon for 50 copper each), they deal a bit more damage, and can likewise be thrown rapidly and penetrate enemies. They deal 6 damage to the 's 1st phase, and can hit the Eye more than once per throw. However, if you're skilled (or lucky) enough to have access to Vile Powder (which is crafted with Vile Mushrooms from the Corruption), you can use that to upgrade your Throwing Knives into Poisoned Knives, which deal 7 damage to the Eye's 1st phase, and can even poison it, inflicting even more damage in the process.
 * Bow & Arrow: Although you cannot fire a bow and arrow as rapidly as you can throw Shurikens or Throwing Knives, it's on here due to its potentially high damage output. A Golden Bow with Flaming Arrows deals 17 damage, which means that it'll deal 11 damage to the Eye's 1st phase. While Flaming Arrows cannot penetrate enemies like Shuriken or Throwing Knives can, it does have a chance of setting enemies on fire, damaging the Eye even further. On the other hand, a Golden Bow with Unholy Arrows (which are made out of normal arrows and Worm Teeth, which are dropped from Devourers) deals 19 damage (13 damage to the Eye's 1st phase), and can penetrate enemies like Shuriken and Throwing Knives can, though it'll travel too fast to damage the Eye multiple times.
 * Musket: If you have Silver Bullets, this could be of use. Regular Musket Balls work as well, but you should have Golden or Silver Armor and Lesser Healing Potions or Healing Potions, as its very slow speed can make it difficult to do consistent damage. With Musket Balls it does 30 damage in the second phase, and 18 in the first.
 * Rare Weapons: Most rare weapons you find in chests in the game will help you a lot. For example you can use an Enchanted Boomerang with your armor (Gold or better) and Healing Potions you should be able to defeat the eye easily. If not, a wooden boomerang wil do, for it can take out the servants.
 * Bone Javelin is also a well used weapon with this fight and can only be obtained in version 1.3.0.1

Arena
Mobility in all directions is important in avoiding the 's attacks, and chances are that you won't have access to such items as Rocket Boots or Hermes Boots. Due to the player's limited jumping skills, it is strongly advised that you build a boss arena that consists of multiple rows of wooden platforms. Finally, the arena should have some tall walls to keep other enemies from entering the arena, though a ceiling isn't required. With no ceiling, Shurikens, Throwing Knives, and Arrows that are thrown upwards would fall back into the arena, and can still damage the during the descent. Keep in mind that the EoC and its Servants are immune to Spikes.

Try to have an open roofed arena because a falling star can do 1000 damage to the !

Also remember to light the arena with torches, as the battle can only take place at nighttime.

The Battle
The can only be summoned during night-time and will disappear without dropping any loot if the player does not kill it before daytime. Therefore, the best time to summon this monster would be soon after nightfall. That way, you'll have pretty much all night to defeat it.

Phase 1
The will try to hover high above the player and shoot out a Servant of Cthulhu every couple of seconds from the iris. The Servants of Cthulhu each have an attack of 12, but only 8 HP, which is low enough for them to die from one Shuriken. While the Eye is summoning Servants, you should be aiming for the pupil, as that's where the Servants will spawn from. If any stray Servants do get too close, then a Broadsword is useful for getting them out of your hair.

After four to six Servants of Cthulhu have been launched, the will start to dive towards the player three times. It has an attack power of 15, which can be damaging if care is not taken. Still, players should try to avoid these dive attacks whenever possible, changing to a higher or lower level if need be. Note that it's possible to lead the Eye's dive attacks by jumping before it attacks.

Phase 2
Once the reaches 1400 HP or below, it'll start to spin around violently, shedding its iris "covering" (and lowering its defense to 0) to reveal a jaw full of sharp teeth, and setting the stage for phase 2 of the battle. While this happens, it is recommended to damage it as much as you can, due to lack of movement and retaliation. While the Eye no longer spawns Servants of Cthulhu during this phase, it hovers closer to the player to ensure that its lunge attacks (which now do 23 damage) are more accurate. It also attacks quicker, making it more difficult to lead its attacks.

However, while the 's speed is usually faster than the player, its acceleration and deceleration is rather poor. A clever player can exploit this by running in one direction, causing the Eye to give chase, then immediately stopping and running in the other direction, causing the Eye to drift away as it struggles to keep up with the player.

Expert Mode
At the beginning of the phase 2, the will release severals Servant of Cthulhus in an addition to his transformation which may interfere with the player's battle. While this happens, it is recommended to get rid of the stray servants first before dealing with the boss itself. It will still lunge towards the player as it was in normal mode regularly.

When damaged enough, the Eye will follow up its lunge attack by supercharging towards the player three times--Which is essentially a much faster variant to its lunge attack. As it continues to get damaged, the Eye will slowly replace its lunge attack and supercharges more frequently up to six times in a row in a more shorter interval and ultimately will continuously supercharge at the target at very low health until either himself or the player dies.

Preparations
One of the easiest ways to defeat the, and maybe the safest way, is to build a track for your minecart. This track must be at least 500 tracks long and the ends must have the bumping pieces. You can use any ranged weapons, everything to attack the from a safe distance. You don't need potions or anything else, because if you use this strategy, you can win without ever been damaged.

Battle
To defeat the, you need to get in your minecart and travel in one direction. Always keep a safe distance to avoid being hit by the 's supercharges. While you travel, you need to use your ranged weapons. If you keep enough distance, you can win without ever been damaged. If you reached the end of the track, you need to use the bumper piece and try to pass the without touching it. Then repeat this strategy.

Trivia

 * The is named after the fictional extraterrestrial entity, Cthulhu, created by horror author H. P. Lovecraft.
 * The correct pronunciation of Cthulhu has long been debated. KAH-THOO-LOO and CHA-THOO-LAH are two commonly argued pronunciations. In reality, Lovecraft intended the name to be unpronounceable, as the creature pre-dated the English language.
 * In patch 1.0.3, during multiplayer, if you pulled out a Suspicious Looking Eye, an would spawn and your Suspicious Looking Eye would not be taken away.
 * A boss resembling the, known as Monoculus, was introduced to the FPS game Team Fortress 2, around Halloween, 2011. Monoculus appeared as a large eyeball shooting smaller eyeball projectiles in a similar manner to the.
 * The first form of the seems to be a larger version of the Demon Eyes, which must be killed to gain Lenses to craft the Suspicious Looking Eye.

Bugs

 * If The is summoned during a Blood Moon using a Suspicious Looking Eye the Dryad may not spawn.
 * On the Console and the mobile edition the boss 4 music will play instead of the boss 1 music (May be intentional). Demonstration: https://everyplay.com/videos/12738706
 * If The is killed too quickly, the defeat message will not show and loot will not spawn. (Needs confirming)
 * If you lead the up to the very top of the map, then drop down rapidly enough for the Eye to leave your screen, it may despawn.
 * A bug that was already fixed made its so that if you clicked on a suspicious looking eye during day it would disappear