|AI Type||Skeletron Prime Head AI|
94158238 (while spinning) 
48 (while spinning) 
|Entering spinning phase|
- Internal NPC ID: 127
"The air is getting colder around you..."
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
10*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.
Arms[edit | edit source]
Behavior[edit | edit source]
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 moving 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, 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 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 if touched: its damage increases to 1000 and its defense raises up to 9999. It will remain in this state until defeated, even if it becomes night again. If defeated, it will drop items normally.
If the player is more than 375 tiles away, Skeletron Prime will start moving downwards and will quickly despawn.
Notes[edit | edit source]
This content is transcluded from Mechanical bosses § Notes.
- When spawning naturally, a mechanical boss spawns exactly 81 seconds 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
10*1/10 (10%) chance of spawning naturally at dusk, the resulting chance for each mechanical boss is initially 3.33*1/30 (3.33%). Once one of them has been defeated, the remaining two have a resulting 5*1/20 (5%) chance of spawning naturally, and after defeating the second one, the last one has the full chance of 10*1/10 (10%).
- It is possible to summon a mechanical boss 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.
- The Bombs fired by the Prime Cannon will only detonate if they hit solid blocks. They will pass through platforms and Planter Boxes without detonating. On the Desktop version and Mobile version, the Bombs do explode upon contact with platforms and on the Desktop version, they also do detonate when hitting Planter Boxes.
Achievements[edit | edit source]
Tips[edit | edit source]
- Standing on platforms / Planter Boxes 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.
- 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. Fast mounts like the Pirate Ship Mount are useful as well.
- 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.
- In fact, as the head is immune to Cursed Inferno but not Ichor, Crimson world players have a clear advantage over Corruption world players in this sense.
Trivia[edit | edit source]
- 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.
- 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 Cursed Inferno and Penetrated, its limbs are not.
- Normally, Skeletron Prime's head has 2000 less HP than Plantera, but in Expert Mode and Master Mode, they both have the same amount.
- The Bombs fired by the cannon resemble the Dirt Bomb, with different coloring on one half.
- – According to the official game lore, 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[edit | edit source]
History[edit | edit source]
- Desktop 220.127.116.11:
- Desktop 1.3.5: Sprite updated. Old sprite was .
- 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:
- Desktop 1.1: Introduced.
- 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 1.1.5536: Introduced.
- 3DS-Release: Introduced.
References[edit | edit source]
- Information taken from the Desktop 18.104.22.168 source code, method
aiStyle == 32
- Information taken from the Desktop 22.214.171.124 source code, method
) There may be inaccuracies, as the current Desktop version is 126.96.36.199.
type == 102
- Information taken from the Desktop 188.8.131.52 source code, method
aiStyle == 36
- In For the worthy, the Bombs do destroy tiles.
Skeletron Prime's velocity is based on its distance to the player, following this formula:
It ranges from 51 mph at a distance of zero tiles to 164 mph at a distance of 137.5 tiles, where it is capped. Information taken from the Desktop 184.108.40.206 source code, method
aiStyle == 32