"You feel the air 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 harder version of Skeletron. It is summoned with the Mechanical Skull at night. Players have until dawn to defeat it. Skeletron Prime can also randomly spawn at dusk in Hardmode if it has not yet been defeated, in this case signaling its approach via the status message, "You feel the air getting colder around you..." or "The air is getting colder around you...".
The boss music is Boss 1.
Skeletron Prime has four limbs which are all immune to the Poisoned and On Fire! debuffs:
- Prime Cannon fires bombs that do not destroy blocks, usually up into the air rather than directly at the player. It usually stays above the player.
- Prime Laser shoots red Death Lasers similar to those of Retinazer and The Destroyer, and is always pointed at a player. It usually stays horizontal to the player
- Skeletron Prime's Prime Saw and Prime Vice both act similarly to the The Twins when they are charging, but the Prime Laser acts similarly to Retinazer or the Wall of Flesh while shooting laser beams.
- Prime Saw usually remains under the player, then swipes upwards or downwards.
- Prime Vice will swipe around wildly, making occasional lunges at the player. It usually remains diagonal to the player.
Skeletron Prime will occasionally enter into a "Rage Mode," in which its attacks become more aggressive:
- Skeletron Prime's Head will grow spikes and start spinning towards the player slowly. Damage and defense is doubled.
- Prime Cannon will aim at the player directly and fire rapidly.
- Prime Laser will fire more frequently.
- Prime Saw will begin homing directly towards the player's location.
- Prime Vice becomes more aggressive and frequently lunges towards the player.
Prime itself is much more mobile than its predecessor, and will regularly move off-screen, which can make it difficult to hit reliably with ranged weapons.
Like Skeletron, if it is not beaten by dawn it begins to continually headspin, dealing enough damage to kill most players in a single hit and having 9999 defense, acting like a Dungeon Guardian.
|| 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.
|| Bona Fide • "You have defeated Skeletron Prime!"
| Defeat Skeletron Prime for the first time.
- The bombs fired by the Prime Cannon will only detonate if they hit solid blocks (they will not destroy blocks). They pass through platforms without detonating.
- If the player is deep enough underground, Skeletron Prime will not spawn randomly, even when the chat message indicates it's coming.
- Unlike Skeletron, Skeletron Prime's defense doubles when its head is spinning.
- Skeletron Prime's arms are not immune to the Cursed Inferno, Penetrated, Celled and Daybroken debuffs. However, its head is immune.
- Skeletron Prime can be defeated by only killing its head.
- If the player summons Skeletron Prime in space or forces him there, he will despawn almost instantly.
- The head of the Skeletron Prime is immune to most of the debuffs, except the Frostburn and Ichor debuffs.
For more elaborate strategies on defeating Skeletron Prime, including Weapon and Arena recommendations, see Guide:Skeletron Prime strategies.
- 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 platforms harmlessly.
- Skeletron Prime can be the most profitable boss in the game, as the Souls of Fright can be crafted into Naughty Present to summon the Frost Moon, netting large amounts of money per 5 souls.
- A tall arena may be more advantageous because it allows the player to flee upwards. This can be useful when Skeletron Prime performs its spin attack, allowing the player to get rid of any arms giving them trouble.
- For changes that affect all the mechanical bosses, see Mechanical_Bosses#History.