Eye of Cthulhu

The Eye of Cthulhu is a pre-Hardmode boss. It is one of the first bosses a player may encounter, as it spawns automatically when a relatively early level of game advancement is achieved. It can also be summoned manually with the Suspicious Looking Eye at night (see Spawn below).

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Spawn
The Eye of Cthulhu can be summoned manually using a Suspicious Looking Eye at night (beginning at 7:30PM in-game time).

It also has a chance of spawning automatically each night, if the following conditions apply:


 * The Eye of Cthulhu has not yet been defeated in the current world.
 * At least one player in the world has at least 200 maximum health and more than 10 defense.
 * At least four town NPCs (including the and ) are present in the world.

If spawning this way, its arrival is announced by the status message "". If the player is sufficiently far underground, the Eye of Cthulhu will not spawn until they return to the Surface. If they remain underground all night, the boss will not spawn at all.

Behavior
The Eye of Cthulhu has two phases, and is able to fly through blocks in both of them. During the first, it attempts to float directly above the player, while spawning 3–4, which drop Hearts and Stars on death. A servant is spawned with the. Afterward, it charges at the player three times in succession, before repeating the cycle.

When the Eye of Cthulhu falls below 50% / health (0 /  / ), it transforms into its second form (shedding its iris into a mouth), which rams the player more aggressively three times, then hangs in the air for a period. It no longer spawns Servants of Cthulhu, and has no defense, but now has increased contact damage. It now lets out a every time it charges.

In, the boss spawns more Servants of Cthulhu than normal, as well as 4–5 servants upon transforming. In the second phase, it will gain an additional powerful rapid chain dash attack, during which it lets out a every time it dashes. These dashes become faster as the Eye of Cthulhu's life decreases, and it can dash nearly continuously when close to death.

If Eye of Cthulhu is not defeated by dawn (4:30AM), if all players die, or if it goes too far off-screen, it will despawn.

Tips

 * The Eye of Cthulhu drops either Demonite or Crimtane Ore. While the corresponding set of armor and a number of tools additionally require Shadow Scales or Tissue Samples respectively—which the Eye does not drop—the sword, bow, axe, yoyo, and fishing pole can be crafted with only the bars.
 * Due to the ease of crafting its summoning item and relatively low difficulty, farming the Eye of Cthulhu is one of the more effective ways of prior to Hardmode. It drops  /  up front, plus ores which can be sold as bars for twice (Demonite) or triple (Crimtane) that amount.
 * The Eye of Cthulhu will only spawn randomly if a player has more than 10 defense. Taking defense-boosting equipment off before dusk can prevent it from spawning randomly.
 * The boss looks at the player it will follow, which can be helpful information in multiplayer.
 * In classic mode, it is most vulnerable during its transformation, because it neither moves nor attacks, but there is only a brief window of opportunity for this. In Expert Mode or above, it sheds a plethora of minions upon transformation, which protects it while it transforms.
 * Because there are no location-based requirements for summoning, defeating multiple Eyes of Cthulhu in an area can be an effective setup for harder boss fights as the dropped Hearts can be picked up mid-fight as needed, though killing an Eye of Cthulhu for that purpose must be balanced with the time it takes away from killing a night-only boss.
 * While it may seem that killing it on a Corruption-generated world would yield more money than doing so in a Crimson-generated world, as it will drop additional Unholy Arrows, Crimtane Ore and Bars sell for a 30% higher price than their Demonite counterparts, making them much more profitable.
 * In singleplayer, the player can repeatedly pause the game using Autopause in order to properly aim at the Eye of Cthulhu during its dash attacks.

Trivia

 * The Eye of Cthulhu, among several other bosses, is based on Cthulhu, a creature first imagined by American author in his short story "".
 * One of the title messages on the PC version refers to this: "Terraria: Cthulhu is mad... and is missing an eye!"
 * The existence of the, an entity spawned by the Moon Lord (who bears resemblance to Cthulhu), may imply that the Eye of Cthulhu is not Cthulhu's actual true eye.
 * This was later overturned by retcons from official game lore and Bestiary entry, both of which confirm it was actually separated from Cthulhu.
 * Assuming that the player is at 5′ 9½″ (1.75 m) in terms of height, the Eye of Cthulhu would be about 13′ (4 m) tall and wide in its first form. The teeth would be 2.6′ (0.8 m) long.
 * The Merchant NPC will mention sensing an evil presence watching him once the requirements to battle the Eye of Cthulhu are met.
 * Although irrelevant to, the Eye of Cthulhu will keep spawning naturally until defeated at least once.
 * It is possible to defeat the Eye of Cthulhu without it ever transforming into its second form, e.g. with late-game weapons or . However, its gore will be unaffected once killed.
 * The Eye of Cthulhu Trophy is a tooth of Eye of Cthulhu, which is only physically seen in its second form.
 * The Eye of Cthulhu seems to have central, an eye condition where there are two colors in the same iris.
 * It was one of the first bosses added, debuting in update 1.0.
 * "Bloody lens and cruel killers created other catastrophic killings", a line from one of H.P.Lovecraft's lesser known novels referenced specifically the eyes of Cthulhu.
 * The Eye of Cthulhu is sometimes abbreviated as "EoC".
 * If the player is using an RGB-keyboard, a mini Eye of Cthulhu can be seen dashing from the left to the right during the battle.
 * The Eye of Cthulhu can sometimes be seen flying in the background as ambiance at night.
 * Two clouds shaped like the Eye of Cthulhu's first and second forms can also appear in the background.
 * The Eye of Cthulhu appears in 2 games from a crossover event: Dungeon Defenders 2 as a boss and in Don't Starve Together, under the name "Eye of Terror" instead.
 * The Eye Of Cthulhu appears in day instead of night in some artwork for Terraria. This is most seen in the PS3 Cover & The Xbox 360 Cover.