"Impending doom approaches..."
Moon Lord is a Hardmode, post-Lunatic Cultist boss. It is Terraria's final boss.
If all players die during the battle, the Moon Lord despawns. It can be re-summoned by completing the Lunar Events again (when the Cultists required to initiate the events re-appear at the Dungeon's entrance), or by using a Celestial Sigil.
While the Moon Lord is alive, its exclusive Moon Lord theme will play.
It summons at the conclusion of the Lunar Events, once the final Celestial Tower is defeated. It can also be summoned manually using a Celestial Sigil. He takes 60 seconds to summon, and during that time the screen will start to blur. The blur effect will intensify until the Moon Lord summons.
The Moon Lord has two hands and a head that must be killed before its "core" becomes available for attack. It positions its two hands on either side of the player some distance away.
Each hand, as well as its head, contain a vulnerable eye-like target that are each periodically closed off and opened via an eyelid. These may only be damaged during their "open" states. Once these parts and then its core are killed, the boss is defeated.
The Moon Lord can teleport to players if all of them get too far out of range.
- The Moon Lord's hands move away from the core and their eyes spawn several Phantasmal Spheres in a line. After a couple seconds, they explode, dealing heavy damage. If the player is far enough away, they simultaneously charge the player before exploding, though they cannot travel at an angle higher than approximately 30 degrees in either direction.
- The hand eyes also spawn multiple Phantasmal Eyes, which move in all directions for a short while, and then home in on the player. Like the Phantasmal Spheres, they cannot travel at an upward angle, so they can be evaded by swerving upwards. They explode upon contact with a block or player.
- The hand eyes also occasionally fire two Phantasmal Bolts in quick succession, which pass through blocks and lead the player, requiring swerves to avoid.
- When attached to Moon Lord's head, the head eye periodically opens for a few seconds, and then fires a Phantasmal Deathray : a large laser that sweeps upward over the player. This is by far the moon lord's most damaging attack. Afterward, the head eye blinks a couple times, and fires two Phantasmal Bolts (similarly to those of the hands), and then closes.
- The mouth periodically attempts to attach it's tongue to the player. The tongue also reaches through solid blocks. Once attached, it spawns multiple Moon Leech Clots , which are monsters that travel from the player to the Moon Lord's mouth. Any Moon Leech Clot that reaches the mouth without being killed returns 1000 health to one of the Moon Lord's parts (one that has not yet been defeated).
- The Tentacle also inflicts the Moon Bite debuff, preventing any life-steal effects from weapons/armor like Vampire Knives or Spectre Armor for 14 seconds (16 seconds in Expert mode).
- When a hand or head target is defeated, it becomes a thorny crevice that deals damage on contact.
- Additionally, when a head or hand target is defeated, a True Eye of Cthulhu spawns, which cycles through four different attacks:
- The eye spawns Phantasmal Eyes, which behave similarly to when before the eyes were defeated.
- The eye spawns 6 Phantasmal Spheres in a circle formation around the eye, which after a few seconds will charge directly at the player.
- The eye fires 2 Phantasmal Bolts at the player, similar to those from the hand eyes
- Finally, the eye charges and fires a lesser Phantasmal Deathray, smaller and dealing significantly less damage.
- Note that while the True Eyes of Cthulhu perform these attacks, they remain stationary, giving players more time to put distance between them and the eyes, and to see attacks coming.
- If the player dies during the Moon Lord's death animation, it will still cause the Moon Lord to despawn and not drop any loot.
- This boss can be summoned with a Celestial Sigil before defeating the Lunatic Cultist in any world where Golem has been defeated.
- If you log out after the message "Impending doom approaches..." The Moon Lord will not spawn.
- It seems that this occurs only some of the time, as players have reported logging out of a world for long periods of time, and still having the Moon Lord spawn.
- The Moon Lord can drop three Melee Weapons, two Ranged Weapons, two Magic Weapons and two Summoner Weapons which are sentries.
For more elaborate strategies on defeating Moon Lord, including Weapon and Arena recommendations, see Guide:Moon Lord strategies.
- If you don't get sick from the Gravitation Potion, you will be moving vertically fast enough to avoid most of its attacks, but it might be difficult to hit his vital parts, unless you use homing capable attacks.
- A good way to avoid his death-ray is to use the gravitation potion to circle around his eye.
- Using a weapon that can attack through blocks, such as Solar Eruption, can mitigate incoming damage while making evasion less complicated. 2 rows of blocks (one to run along and one above to protect from lasers) can be quite effective.
- A large portion of the Moon Lord's attacks, including the laser he emits from his head, are incapable of passing through blocks. Consider seeking cover to avoid these attacks during the fight.
- The Moon Bite debuff, which prevents regenerative abilities, is reliant on a tentacle making contact with the player. It is possible to move outside of its maximum range, avoiding the debuff and allowing effects to once again heal the player. One such method is by using asphalt. Another one, if you have beaten all the Mechanical Bosses in expert mode, is to make a huge Minecart track with bumper ends and use the Mechanical Cart. The bumper ends makes it easier to turn when the track ends, making it even harder to be reached by his tentacle. Also, the cart will be able to shoot red lasers at his hands because the hands are almost always in front of you.
- It is best to start by damaging the two hands until they are both at very low health. Next, kill the head. As soon as you kill the head, kill the two near-death hands. This will cause the eyes to come out of the hands at the second half of the fight, increasing your survivability during the first half.
- Since the hands will begin to start dealing melee damage after they are defeated, running away on an asphalt sky bridge will become an issue if not properly prepared to dodge the hands.
- It is unwise to use Vampire Knives or the Spectre Hood as the Moon Bite debuff occurs very often, which disables life steal from these weapons/items.
- Unlike every other boss (except The Destroyer), the Moon Lord does not despawn if you go too far away from him. Rather, he teleports to where you are.
- When the Moon Lord teleports, he always teleports to the player with the shortest distance from him.
- Since he teleports, it may be useful to have a nurse near your spawn point
- You can use rails going across your world to avoid the attacks (You can also use platforms too).
- Owning a Rod of Discord can provide a great deal of assistance, as it can be used to easily evade the Moon Lord's Phantasmal Death Ray. Use it sparingly though, as Chaos State can kill an unaware user.
- The Cosmic Car Key can provide a huge advantage, as it makes avoiding his attacks easier than on the ground, and also goes slightly faster than Moon Lord, however it is advised to kill his head first, as it is difficult to avoid the Phantasmal Deathray with this strategy.
- Despite a mid-development comment by Cenx that this would not be the case, the Moon Lord resembles common depictions of Cthulhu, a creature first imagined by H. P. Lovecraft in his story, The Call of Cthulhu. Fans commonly speculated prior to the release of 1.3 that Cthulhu would be the final Terraria boss (which in turn arose partly due to an early concept design floated by the development team). Cenx later stated that the Moon Lord is more like Cthulhu's brother. 
- Terraria's final boss was originally going to be the Moon itself descending on the world, but Cenx later stated that this idea had been scrapped. 
- Despite being the final boss of the game, the Moon Lord's monetary drops are less than the Wall of Flesh on normal mode, and absent on expert.
- Despite being the final boss, Moon Lord has the lowest amount of status immunities, being immune only to Confusion (tied with many other bosses who also share the same immunity).
- The Moon Lord's resemblance and relation to Cthulhu have a basis within Lovecraft's "Cthulhu Mythos" as Cthulhu has two brothers, an identical twin named Kthanid and a half brother named Hastur, both taking a form similar to Cthulhu's, though the Moon Lord is more than likely in reference to Hastur as both have a trademark sign that signals his arrival (see the celestial sigil and the yellow sign) as well as the fact that unlike his twin, Kthanid is "as good as his brother is evil" making it unlikely that he would attack the player.
- 126.96.36.199: Attacks now follow their own immunity cooldown.
- The Moon Lord will now teleport to the player once they are far enough away.
- You can no longer escape from the Moon Lord's wrath. (e.g. teleport home to heal and fight the Moon Lord at full health)
- Body parts now properly show display names.
- Cultists cannot respawn while Moon Lord is alive or spawning
- 188.8.131.52: The Moon Lord's leeching effect has been massively buffed, and he applies a debuff that prevents any healing from weapons.
- 184.108.40.206: The death message now properly displays "Moon Lord has been defeated!", instead of "Moon Lord Core has been defeated!".