Zero

ZeroDoomsday Construct

Statistics

Type	Boss
Environment	The Void
AI Type	Zero AI
Damage	50 / 69
Max Life	350,000
Defense	150
KB Resist	100%
Immune to	All debuffs

Drops

Coins	55

• Item (Quantity)Rate
• Unstable Singularity(Ancients Awakened) (20-30)
  100%
• Apocalyptite Plate(Ancients Awakened) (20-30)
  100%
• One of the following fifteen items will be dropped
• Doomsday Terratool(Ancients Awakened)
  8%
• Rift Shredder(Ancients Awakened)
  8%
• Event Horizon(Ancients Awakened)
  8%
• Omega Volley(Ancients Awakened)
  8%
• Vortex(Ancients Awakened)
  8%
• Blackhole Blaster(Ancients Awakened)
  8%
• Neutralizer(Ancients Awakened)
  8%
• Singularity Arrow(Ancients Awakened)
  8%
• Unstable Power Cell(Ancients Awakened)
  8%
• Genocide Cannon(Ancients Awakened)
  8%
• Reality Cannon(Ancients Awakened)
  8%
• Gigataser(Ancients Awakened)
  8%
• Void Star(Ancients Awakened)
  8%
• Nova Focus(Ancients Awakened)
  8%
• Broken Zero Weapon(Ancients Awakened)
  8%
• Zero Trophy(Ancients Awakened)
  10%
• Zero Mask(Ancients Awakened)
  10%

Map Icon

Strange Machine

Statistics

Type	Enemy
Environment	The Void
AI Type	No AI
Damage	0
Max Life	100 (Invincible)
Defense	100
KB Resist	100%
Immune to	All debuffs

"ZER0 UNIT ACTIVATED. ENGAGE D00MBRINGER PR0T0C0L."

Zer0 is a post-Moon Lord, Ancient-tier Boss fought in The Void.

Spawn

Zer0 is initially found as a dormant Strange Machine in The Void. It can be found at any point in the game, but cannot be interacted with in any way.

Once the player has the means to do so, using the Doomsday Tesseract in The Void will activate the Strange Machine, which turns into Zer0. If Zer0 has already been defeated, it will simply summon Zer0.

Behavior

Zer0 acts like a sentry, with its weapons circling around it. As long as Zer0 has active weapons, its main body will be protected by an invincible shield.

• Zer0 has 8 possible weapons it can start the fight with. Once summoned, it will use 6 random weapons.
  • Nova Focus, which fires a continuous death ray.
  • Genocide Cannon, a cannon that shoots deadly rockets.
  • Omega Volley, which fires rapid barrages of bullets.
  • Void Star, which fires a homing projectile that summons a "black hole" to suck in the player, holding them in one spot.
  • Reality Cannon, which shoots lasers.
  • Rift Shredder, which fires triangular projectiles that home in before exploding into a ring of lasers.
  • Gigataser, which shoots lightning bolts similarly to the weapon with the same name
  • Neutralizer, which fires three arrows at the player.
  • When a weapon is destroyed, it will become a Broken Weapon, which fires spreads of bolts.
• When the weapons are destroyed, all previous Broken Weapons vanish, 5 Broken Weapons spawn, and Zero lowers its shield.
• When it has its shield lowered, Zer0 will occasionally teleport to new locations around the player while using the following attacks:
  • Opens up and fires powerful beams along the cardinal or ordinal directions, signified by warning lasers.
  • Rapidly fires lasers at the player.
• At 70%, it raises its shield again, and creates 7 of the possible weapons
• Upon the defeat of the weapons, Zer0 lowers it again, and will have 6 Broken Weapons
• At 33%, it will re-raise the shield, and have all 8 of its weapons.
• Upon their defeat, it will have 7 Broken Weapons.

Quotes

Pre-Battle

• "ERROR. PLAYER.GETMODPLAYER<AAPLAYER>(MOD).ZONEVOID == FALSE. PLEASE TRY AGAIN LATER." (When attempting to summon Zer0 outside the Void)

Zer0 Quotes

• "ZER0 UNIT ACTIVATED. ENGAGE D00MBRINGER PR0T0C0L." (When Zero is summoned)
• "INITIATING BACKUP WEAPON PROTOCOL." (When Zero regenerates its arms)

Post-Battle

• "TARGET LOST. RETURNING TO ORBIT." (When the player leaves the Void during battle)
• "TARGET NEUTRALIZED. RETURNING TO ORBIT." (When the player is killed)
• "D00MSDAY PR0T0CALL MALFUNCTION. MAIN.EXPERT-MODE = FALSE." (When Zero is defeated on Normal Mode)
• "DISTRESS SIGNAL RECIEVED." (By Infinity Zero after Zero is defeated)

Awakened Phase: Zero Protocol

Zero ProtocolDark Cipher

Statistics

Type	Boss
Environment	The Void
AI Type	Zero Protocol AI
Damage	167
Max Life	500,000
Defense	70
KB Resist	100%
Immune to	All debuffs

Drops

Coins	3

• Item (Quantity)Rate
• Treasure Bag(Zero)

  • Broken Code

  100%

Map Icon

Expert Mode-Only Content: This section applies only to Expert mode and Expert mode worlds.

"PHYSICAL ZER0 B0DY IN CRITICAL C0NDITI0N. DISCARDING AND ENGAGING D00MSDAY PR0T0C0L."

Zero Protocol is an Expert Mode exclusive second form of Zero. It has an entirely different AI from its non-expert phase, so extreme caution is advised.

Behavior

• Zer0 hovers near the player, firing glitched blasts or rockets that slightly home. The blasts explode on impact, while the rockets pierce tiles and have much stronger homing abilities.
• Zer0 frequently teleports to new locations, especially upon taking damage.
• Fires 4 rays around itself, telegraphed by warning beams. Below 50% HP, this fires eight rays in a star pattern around itself.
• Summons two rows of portals above and below itself that fire spaced vertical death rays after a delay. Alternatively, summons two columns of portals to the left and right of itself that fire spaced horizontal death rays after a delay. Below 50% HP, this summons portals all around itself that form a grid of lasers.
• Fires several homing electric orbs that explode into bursts of electric bolts after a while.
• Creates several "3CHO" clones around itself. Zer0 Protocol and the 3CHO enemies will all attack with X-shaped deathray bursts after a short delay to create a web of lasers. The clones can be destroyed before they fire, and will self-terminate after the attack ends.
• After a short dialogue chain, summons four Zer0 Self Orgnazation minions. Zero will then fire a massive death ray at the player while each minion fires four sweeping deathrays around itself. The minions will then follow the player, teleporting around and firing 4-way lasers along the cardinal or ordinal directions.
  • Zero will not summon more minions if any Zer0 Self Orgnazation units are still alive.

Quotes

Pre-Battle

• "ERROR. PLAYER.GETMODPLAYER<AAPLAYER>(MOD).ZONEVOID == FALSE. PLEASE TRY AGAIN LATER." (When attempting to summon Zer0 outside the Void)

Zero Protocol Quotes

• "D00MSDAY PR0TOCAL ACTIVATED MANUALLY. TERMINATI0N SYSTEMS AT FULL P0WER." (Upon summoning Zer0 Protocol with an ERR0R_NULL)
• "PHYSICAL ZER0 UNIT IN CRITICAL CONDITI0N. DISCARDING AND ENGAGING D00MSDAY PR0T0C0L." (When Zer0 is defeated in Expert Mode, commencing Zer0 Protocol)
• "SELF ORGNAZATION CHARGING COMPLETE." (preparing to summon minions)
• "BOOTING IN SELF ORGNAZATION MODE."
• "ALLOW C:\TERRARIA\AAMOD\ZERO\PROTOCOL\SELF-ORGNAZATION.EXE?" <Y/N>
• "[Y]" (spawning Zero Self Organazation units)[sic]
• "=== C A R N A G E ===" (firing lasers alongside minions)

Post-Battle

• "TARGET LOST. RETURNING TO ORBIT." (When the player leaves the Void during battle)
• "TARGET NEUTRALIZED. RETURNING TO ORBIT." (When the player is killed)
• "DISTRESS SIGNAL RECIEVED." (By Infinity Zero after Zero is defeated)
• "CHEATER ALERT CHEATER ALERT. NO DROPS 4 U" (When Zero Protocol is defeated on Normal Mode)

Aftermath

• Nulls start spawning in The Void, which drop Unstable Singularity; creating a way to obtain them without fighting Zero again.
• The background of The Void changes, and Infinity Zero appears as it is slowly approaching.

Notes

• All of the projectiles from Zer0's weapons pierce tiles for the first few seconds of their lifetimes to prevent players from locking it in a box of tiles and blocking all its attacks. The only exception to this is the ray from the Nova Focus, which does not pierce.
• Despite being labelled after Akuma and Yamata in game as well as on this wiki, it is only ordered this way due to being alphabetically placed after those two, and as such, Zero is meant to be fought at the same level as the chaos ancients, and as such, can be fought before those 2 without any major difficulty.
  • And also because the materials required for its summon item only requires Post-Equinox Worms bars and bars dropped by the Searchers, it can be fought right after the Equinox Worms, and doesn't requires Sisters of Discord to be defeated, unlike the chaos ancients.

Tips

• The naturally generating islands in The Void can provide cover from a lot of Zer0s projectiles.
• It is recommended to refrain from moving too quickly, as Zer0 may teleport in front of the players path.

Trivia

• Zer0 was the first Ancient Boss and second Post Moon Lord Boss added to the mod, being added in Beta 0.3.
• Zer0’s Design is based on The Fabrication Machine from the animated movie 9. Originally, however, Zero was going to be based on 0-2 from Kirby and the Crystal Shards.
• Zer0 is actually one of many ZER0 units dispatched by Infinity Zero.
• After being resprited 4 times, Zero's final resprite was made by Anoterontas.
• Some of Zer0's dialogue is a reference to programming language.
• Zero is going to receive new designs and name in the official remake.
  • In Awakened Light, Zero is going to be moved to late Hardmode while Zero Protocol stays in Post-Moon Lord tier.