Skeletron Prime

Skeletron PrimeHardmode exclusive

Map Icon

 Classic

 Expert

 Master

Statistics

Type	Boss
Environment	Surface + Night Space + Night
AI Type	Skeletron Prime Head AI
Damage	47/79/119 (contact) 94158238 (while spinning)
Max Life	28000/42000/53550
Defense	24 48 (while spinning)
KB Resist	100%
Immune to

Drops

Coins	12 GC30 GC

• Item (Quantity)Rate
• Soul of Fright (25–40)
  100%
• Hallowed Bar (15–30)
  100%
• Horned God Mask(Old-gen console version)
  14.29%
• Greater Healing Potion (5–15)
  100%
• Skeletron Prime Mask
  14.29%
• Skeletron Prime Trophy
  10%
• Treasure Bag(Desktop, Console and Mobile versions)(Skeletron Prime)
  100%
• Mechanical Battery Piece(Desktop, Console and Mobile versions)
  100%
• Skeletron Prime Mask
  14.29%
• Soul of Fright (25–40)
  100%
• Hallowed Bar (20–35)
  100%
• Gold Coin (12)
  100%
• Robotic Skull(Desktop, Console and Mobile versions)
  25%
• Skeletron Prime Relic(Desktop, Console and Mobile versions)
  100%

Sounds

Hurt
Killed
Entering spinning phase

• Internal NPC ID: 127

 “The air is getting colder around you...” 

Not to be confused with Skeletron, the pre-Hardmode boss.

Skeletron Prime is a Hardmode mechanical boss which is essentially a more difficult version of Skeletron. It consists of a head and four limbs, but, similarly to Skeletron, only the head needs to be defeated to defeat the boss.

Skeletron Prime can be summoned manually using a Mechanical Skull at night (7:30 PM to 4:30 AM). It also has a 1/10 (10%) chance to spawn naturally at dusk once a Demon or Crimson Altar has been destroyed, as long as it has not yet been defeated at least once in the current world. If spawning this way, its arrival is announced by the status message "The air is getting colder around you...".

If Skeletron Prime is not defeated by dawn, it will behave much like a Dungeon Guardian: It will cease using its limbs and instead charge at the player at extremely high speeds, dealing usually lethal damage upon contact.

While Skeletron Prime is alive, the music Boss 1 will play. When Otherworldly music (Desktop, Console and Mobile versions) is enabled, the track Boss 2 (Otherworldly) will play instead.

Arms

Prime Cannon

 Classic

 Expert

 Master

Statistics

Type	Boss Part
Environment	Surface + Night Space + Night
AI Type	Prime Cannon AI
Damage	30/51/76 (contact) 80160240 (Bomb)
Max Life	7000/10500/13387
Defense	23
KB Resist	100%
Immune to

Projectile created

Projectile created

Projectile created

• Skeletron Prime Bomb
  

Sounds

Hurt
Killed
Bomb launch
Bomb explosion

• Internal NPC ID: 128
• Internal Projectile ID: 102

Prime Saw

 Classic

 Expert

 Master

Statistics

Type	Boss Part
Environment	Surface + Night Space + Night
AI Type	Prime Saw AI
Damage	56/95/142
Max Life	9000/13500/17212
Defense	38
KB Resist	100%
Immune to

Sounds

Hurt
Killed

• Internal NPC ID: 129

Prime Vice

 Classic

 Expert

 Master

Statistics

Type	Boss Part
Environment	Surface + Night Space + Night
AI Type	Prime Vice AI
Damage	52/88/132
Max Life	9000/13500/17212
Defense	34
KB Resist	100%
Immune to

Sounds

Hurt
Killed

• Internal NPC ID: 130

Prime Laser

 Classic

 Expert

 Master

Statistics

Type	Boss Part
Environment	Surface + Night Space + Night
AI Type	Prime Laser AI
Damage	29/49/73 (contact) 50100150 (Death Laser)
Max Life	6000/9000/11475
Defense	20
KB Resist	100%
Immune to

Projectile created

Projectile created

Projectile created

• Death Laser
  

Sounds

Hurt
Killed
Attack

• Internal NPC ID: 131
• Internal Projectile ID: 100

Behavior

Skeletron Prime's appearance during the spinning phase.

Skeletron Prime's head constantly endeavors to remain between 31.5 and 12.5 tiles above the player and within 6.25 tiles of either side of the player. It can accelerate infinitely in order to move back into this area. The head does not actively attempt to make contact with the player.

Skeletron Prime's four limbs all have unique attacks:

• Prime Cannon fires bombs every 2.33 seconds that do not destroy tiles, usually up into the air rather than directly at the player. It usually stays above the player.
• Prime Saw usually remains under the player, moving up and down.
• Prime Vice will swipe around wildly, making occasional lunges at the player. It usually remains diagonal to the player.
• Prime Laser shoots red Death Lasers every 3.33 seconds, similar to those of Retinazer and The Destroyer, and is always pointed at a player. It usually stays horizontal to the player.

Every 10 seconds, Skeletron Prime will enter a spinning phase for 6.67 seconds, in which its attacks become more aggressive:

• Skeletron Prime's head will grow spikes and start spinning towards the player at 10 mph, exactly like how its pre-Hardmode counterpart Skeletron does. Damage and defense are doubled to 94 / 158 / 238 damage and 48 defense. In Expert Mode(Desktop, Console and Mobile versions), the base spinning speed is 31 mph and is increased the further the player is away, up to a maximum of 76 mph at a distance of 37.5 tiles.
• Prime Cannon will aim at the player directly and decrease its cooldown between firing to 0.67 seconds.
• Prime Saw will begin homing directly towards the player's location.
• Prime Vice becomes more aggressive and frequently lunges towards the player.
• Prime Laser will fire lasers every 1.33 seconds.
• Skeletron Prime lets out a roar every time it enters the spinning phase.

Upon reaching dawn (4:30 AM), Skeletron Prime will enrage and permanently behave like a faster Dungeon Guardian, increasing its velocity and usually killing the player instantly upon contact: its damage increases to 1000 and its defense is increased to 9999. It will remain in this state until defeated, even if it becomes night again. Killing Skeletron Prime in this form still counts as defeating it and it will drop its items normally.

If the player is more than 375 tiles away, Skeletron Prime will start moving downwards and will quickly despawn.

Notes

This content is transcluded from Mechanical bosses § Notes.

• When spawning naturally, a mechanical boss spawns exactly 81 in-game minutes (at 8:51 PM) after the status message has appeared. Being in a layer lower than the Surface at that moment, or, in singleplayer, exiting the world during that timespan, will prevent the boss from spawning naturally.
• With the 1/10 (10%) chance of spawning naturally at dusk, the resulting chance for each mechanical boss is initially 1/30 (3.33%). Once one of them has been defeated, the remaining two have a resulting 1/20 (5%) chance of spawning naturally, and after defeating the second one, the last one has the full chance of 1/10 (10%).
• An Eye of Cthulhu naturally spawning will take precedence over a mechanical boss naturally spawning.
• A Lantern Night(Desktop, Console and Mobile versions) occurring will prevent a mechanical boss from naturally spawning. However, summoning a mechanical boss using one of the summon items will cancel out the Lantern Night, just like any other boss summon.
• In a Get fixed boi(Desktop, Console and Mobile versions) world, the player cannot summon the mechanical bosses separately, they have to summon the Mechdusa instead.
• It is possible to summon a mechanical boss in pre-Hardmode if the summoning item is brought in from another world. However, if the Wall of Flesh has not been defeated, Plantera's Bulbs will not start spawning.
• (Old-gen console and 3DS versions) The Bombs fired by the Prime Cannon will only detonate if they hit solid blocks. They will pass through platforms without detonating. On the  Desktop version,  Console version, and  Mobile version, the Bombs do explode upon contact with platforms as well as Planter Boxes.

Achievements

Buckets of Bolts • “Defeat the three nocturnal mechanical menaces: the Twins, the Destroyer, and Skeletron Prime.”

Defeat all three mechanical bosses. (Desktop, Console and Mobile versions)

Category: Slayer

Mecha Mayhem • “Do battle against the Twins, the Destroyer, and Skeletron Prime simultaneously and emerge victorious.”

Defeat all three mechanical bosses simultaneously in a single battle. (Desktop, Console and Mobile versions)

Category: Challenger

Slayer of Worlds • “Defeat every boss in Terraria.”

Defeat every boss in the game. (Desktop, Console and Mobile versions)

Category: Challenger

Bona Fide • “You have defeated Skeletron Prime!”

Defeat Skeletron Prime for the first time. (Old-gen console version)

Back for Second • “You have defeated all the prime bosses twice!”

Defeat all of the mechanical bosses twice.

Tips

For more elaborate strategies on defeating Skeletron Prime, including weapon and arena recommendations, see Guide:Skeletron Prime strategies.

• Unhindered movement is crucial when Skeletron Prime's head starts spinning, as it deals double the regular damage. Wings greatly aid in moving vertically, and flattened terrain or a sky bridge are convenient for horizontal movement.
• Although it is a little more time-consuming, focusing on the arms first is very rewarding. Once Skeletron Prime's head is no longer shielded by anything, the fight becomes a lot easier. Prioritize damage on the arm which is causing the most damage or disruption, so it can be destroyed and removed from the fight as quick as possible.
• A good idea is to focus on the Prime Laser first, as it is harder to dodge than the other limbs.
• Due to Skeletron Prime's overall high defense, inflicting it with Ichor is effective, as it is not immune to it. Note that most Ichor weapons lack in damage compared to other weapons, so they should only be used periodically for inflicting the debuff.
• (Old-gen console and 3DS versions) Standing on platforms far from blocks can mostly nullify the effects of the Prime Cannon, as its projectiles only detonate on blocks, while passing through those tiles harmlessly.

Trivia

Skeletron Prime's head, arms, and all four limbs.

• Skeletron Prime will open and shut its mouth for the entire duration of the battle, except for when its head is spinning. This is a purely cosmetic effect.
• Skeletron Prime's joints that connect its arms and head continuously emit fire and smoke particles in a similar manner to that of Skeletron's joints.
• It is the only mechanical boss whose name contains the pre-Hardmode boss's name. Furthermore, it is the only mechanical boss to share boss music with its pre-Hardmode variant. Additionally, its name does not begin with the word The, unlike the other two mechanical bosses.
• Unlike Skeletron, Skeletron Prime's defense doubles when its head is spinning.
• Although Skeletron Prime's head is immune to (Old-gen console and 3DS versions) Cursed Inferno and Penetrated(Desktop, Console and Mobile versions), its limbs are not.
• Normally, Skeletron Prime's head has 2000 less health than Plantera, but in Expert Mode(Desktop, Console and Mobile versions) and Master Mode(Desktop, Console and Mobile versions), they both have the same amount.
• Skeletron Prime is the only boss with more than two arms.
• The sprite file for Skeletron Prime's arms is named Arm_Bone_2.
•  – According to the Terraria lore pages, Skeletron Prime was one of the three mechanical recreations of Cthulhu's missing organs. It is a recreation of part of Cthulhu's skeleton.

• The Bestiary entry for Skeletron Prime: "Mechanically reconstructed for reviving Cthulhu, this Skeletron has more arms than ever before, and a variety of fierce weapons."

See also

• The Destroyer
• The Twins
• Mechdusa

History

For changes which affect all the mechanical bosses, see mechanical bosses history.

 Desktop version

• Desktop 1.4.1.2: Prime Cannon's Bombs will now explode on contact with Planter Boxes.

• Desktop 1.4.1: Skeletron Prime is now vulnerable to Cursed Inferno.

• Desktop 1.4.0.1:
  • Skeletron Prime AI overhaul: will now act similar to Skeletron and spin faster in Expert Mode.
  • Prime Cannon's Bombs now explode on platforms rather than going through them.
  • Added two Master Mode drops, Robotic Skull and Skeletron Prime Relic.

• Desktop 1.3.5: Sprite updated. Old sprite was .

• Desktop 1.3.0.1: Added an Expert Mode drop, Mechanical Battery Piece.

• Desktop 1.2.3:
  • Increased health, damage and defense of most parts.
  • Now drops Skeletron Prime Mask.
  • Fixed bug where the player could defeat Skeletron Prime by destroying the Prime Cannon hand and not Skeletron Prime itself.

• Desktop 1.2:
  • Now has a chance to spawn naturally at dusk with the message: "The air is getting colder around you...".
  • Will now drop 20–40 Souls of Fright, instead of 20–30.
  • Now drops Skeletron Prime Trophy.
  • Reduced health, damage and defense of all parts and head.

• Desktop 1.1: Introduced.

 Console version

• Console 1.0.933.1: Added Expert mode drop, Mechanical Battery Piece. ()

• Console 1.0.750.0: Added Expert mode drop, Mechanical Battery Piece. ()

• Console-Release: Introduced.

 Mobile version

• Mobile 1.1.5536: Introduced.

Nintendo 3DS version

• 3DS-Release: Introduced.