There are two ways to spawn Skeletron Prime:
- If Skeletron Prime has not been defeated in a particular world, it will sometimes spawn at night on its own. If this happens, then it will be heralded by the message "You feel the air getting cold around you..." appearing at dusk. So long as the player is not underground, the boss will spawn shortly after this message appears.
- If the player is underground when they receive this message, Skeletron Prime will only spawn if they arrive above ground at the time he would normally spawn. If they venture above ground after that time, he will not spawn.
- Using a Mechanical Skull (not to be confused with Suspicious Looking Skull) at night will spawn Skeletron Prime.
When killed, he will drop about 20-40 Souls of Fright, 14 Gold Coins, and 5-15 Greater Healing Potions. He will also drop 20-30 hallowed bars and has a rare chance to drop a Skeletron Prime Trophy, or a Skeletron Prime Mask. Like Skeletron, the hands do not drop anything.
If all players are killed, Skeletron Prime will disappear underground. The only way to see him again is to summon him.
Skeletron Prime is comprised of five individual parts: the head and four different limbs. This makes it the most complex monster in Terraria yet.
This is the part with the most HP and is also the main part of the boss — when this part is destroyed, Skeletron Prime is defeated. Its attack pattern is the same as Skeletron: it will usually keep its distance from the player, but will periodically start spinning and lunge at them for increased damage and defense. However, unlike Skeletron, it grows spikes from its head when attacking, which give it a slightly larger range, so care must be taken to not get too close.
The Prime Laser orbits around the head, shooting a low-damage beam at the player every time it is facing them. With 6,000 HP and a low amount of defense, it is the least threatening of the boss's weapons, although it is not to be underestimated. It will sometimes lock on to the player and shoot several beams in succession, so active dodging is recommended.
The Prime Cannon is slightly more resistant than the Laser (7,000 HP) and will periodically shoot prime bombs that deal average damage to a player (about 30 per shot with a full Adamantite set). Depending on its own state and that of the other limbs, it will start replacing the single shots with volleys of 3-5 cannonballs, so it is best to keep moving, especially when the boss is directly above the player. The bombs inflict the Debuff "Confused" and other ailments.
Note: The cannon balls only explode on contact with a solid block, and will pass straight through Wood Platforms, so standing on an aptly-built line of them will render this weapon useless. Using a form of flying (Gravitation Potion, for example), will also allow you to avoid the cannon's balls.
The Prime Vice is Skeletron Prime's main melee weapon. When near the player, it will make a lunge at them. It has 9,000 HP and greater defense than the ranged weapons, and also has a rather large hitbox, so it will likely intercept part of the bullets shot at the head.
The Prime Saw is the boss's most dangerous weapon. It has 9,000 HP, the most defense of all limbs, and its attack is a lunge at the player that, when it connects, scores a rapid streak of powerful hits. As long as the Prime Saw is on the field, extra care should be taken in order to prevent getting too close, lest the player quickly loses a lot of health to this attack. A Cross Necklace can be used to lessen the damage done by this weapon due to the fact that it increases the duration of invincibility after being attacked.
Pointers and Behavior
- Unlike most summonable bosses, Skeletron Prime will not despawn at dawn, but (just like Skeletron) will gain a huge defense and offense buff and will start to relentlessly chase the player (pretty much acting like the Dungeon Guardian), ultimately killing them in one blow. It is, therefore, best to summon him just after sunset (7:30 PM in-game). This way, they will have a maximum of 15 minutes to fight the boss.
- Skeletron Prime will react to most attacks by backing away from the player, often off-screen so using fullscreen mode with a large resolution is recommended.
- The Vice and Saw will briefly detach from the body whenever they attack the player: this is a good chance to score some hits at the head without the risk of the shots being blocked.
- Like Skeletron, the hands' hitbox doesn't include the arms, so it is safer and simpler to just jump over them rather than completely move out of the way.
- Avoid using explosives like Hellfire Arrows or Grenades; a melee attack could suddenly block the projectile and the splash damage could hurt you badly.
- Each part of the boss can target a different player; This allows a team of players to split them up, causing them to spread out and become less effective.
- Be careful using rapid-Mana costing weapons as you can run out of Mana very quickly. Always have an alternative like long reach melee weapons (like Vampire Knives) or ranged weapons when you do.
- Since the battle can drag for quite a bit, it is advisable to wear the best pieces of armor available, since Skeletron Prime has a huge arsenal of attacks, it is likely that the player will take many hits during the battle, so maximizing defense should be the main priority.
- Bring powerful ranged weapons; the Megashark will deal lots of damage quickly, while the Hallowed Repeater (or the Adamantite Repeater if you have not yet defeated any of the Mechanical Bosses) will let you exploit the buff from Archery Potion and use the special attacks of several arrows to quickly deal with all the parts. A Star Cannon can deal large amounts of damage but would require a large amount of ammunition to be a viable option.
- For magic users, recommended spells are Golden Shower, Crystal Storm, Nimbus Rod and Cursed Flames.
- For melee users, a powerful spear like Adamantite Glaive or Titanium Trident is recommended, because you can attack while moving backward and deal thousands of damage easily when Skeletron Prime spins his head.
- You can use a broadsword as an alternative for the spear, but that will increase the chance of being injured by the head and may cause a swift death.
- If you have the materials, try using Frost Armor, Golden Shower, 5-15 Greater Healing Potions, and a Megashark. Use Golden Shower to give the boss the Ichor Debuff and switch with Megashark for higher DPS. Repeat when the debuff wears off.
- Other than attacking the player and blocking their way, the hands will protect the head against any non-piercing weapon: Holy Arrows, Crystal Bullets and/or the Cursed Flames spell are a good way to pierce through its defenses and damage the head and arms simultaneously.
- Since Skeletron Prime tends to move back and forth relative to the player, it is best to stand ground in one place (preferably fitted with a heart/star generator) and go after the boss every time it is in range, then coming back down and waiting for it to descend again. Rocket Boots and Wings greatly aid this strategy.
- Once the boss is down to one or no arms, the head can be easily finished off with a spear or flail, since they can score several hits per use and the head's movement is predictable enough.
- If you don't want to make an arena, you could also try to fly around with Gravitation Potions and Wings while shooting Skeletron, which also makes it easier to visit the Nurse when necessary without risking her death. Summon Skeletron and fly around dodging.
- For Melee users, it is recommended to attack Skeletron's arms first, since when those are gone the fight is much simpler.
- Craft the Golden Shower and hit Skeletron Prime's head (Keep hitting him until you are out of Mana). Then if you have a Megashark and some bullets, aim for his head and shoot him (It can help when he is spinning). Once his head is yellow (because of the Golden Shower), that means he has lowered defense. Keep shooting the Megashark until you are back at full mana or his head has turned back to normal color. Once you have your mana back, hit him with the Golden Shower (you will not be able to use it if you do not have mana). Shoot him with the Golden shower and dodge his attacks, repeating the strategy over again until you defeat him. A tip is to fight Skeletron Prime on a bridge or flat surface.
- A thing to remember is that Skeletron Prime's head is immune to the Cursed Inferno Debuff, but its hands are not. Bring along Cursed Bullets/Cursed Arrows if you are a ranged user, or the Cursed Flames weapon of you are a magic user. If you are playing console/mobile, you can also use the Sharanga with Wooden Arrows, as the Sharanga will transform the arrows into Spectral Arrows, which are essentially stronger Cursed Arrows.
- It is not recommended to use the Flower of Fire, as the Prime Vice and Prime Saw can easily block the projectile, and its On Fire! debuff is weaker than the Cursed Inferno.
- The Crystal Ball's Clairvoyance buff can be useful to Magic users. For melee users or gunners, the Wrath Potion can help. For archers, the Archery Potion may assist.
- At dawn, Skeletron Prime gains an incredible damage and defense boost. Thus, players should refrain from summoning him close to dawn.
- There is a chance that any monster during Hard Mode will drop the Mechanical Skull if the boss has not been defeated in that world.
- It seems Skeletron Prime, as well the other two mechanical bosses, only starts its natural spawn attacks at night after the first demon altar is destroyed. (needs confirmation)
- Skeletron Prime has a head and hands made of metal, while its arms remain made of bone.
- The name seems to be a reference to Megatron and Optimus Prime from the Transformers franchise, as well as Skeletor from the He-Man television series.
- It is possible that when he dies, Skeletron Prime will vanish, not drop anything, and his limbs can still be attacked for a few seconds despite him being dead.
- Rarely, Skeletron Prime will not spawn when the player has used the Mechanical Skull or the icon, "The Air Is Getting Cold Around You...", has appeared.
- The player can force this to happen by saving and exiting as soon as the icon, "The Air Is Getting Cold Around You...", appears. After this is done, the player can reload the world without Skeletron Prime spawning.
- sometimes the Hallowed bars will just disappear when they are collected (needs confirmation, possibly mobile only).
- Sometimes at dawn, Skeletron Prime (Guardian form) will fly above you and make it easy to kill him with a sword, however, you only do 1 damage.
- Sometimes when fighting: The Destroyer, The Twins, Ocram, and Skeletron Prime all at once, he will disappear.
- Sometimes while wearing the Turtle armor at dawn he rushes the player, doing 9999 damage, but, due to the Turtle Armor's high Thorns Effect, Skeletron Prime will also die, and drop the items, even if he has 9999+ health.
- Sometimes when flying up to world height and making Skeletron disappear above the screen, Skeletron Prime will lose all his body parts except for his Saw.
- Rarely, Skeletron Prime will spawn, with his arms all dead, left only with his head. Skeletron, has this bug as well.
- Sprite updated.
- Head health increased from 25,000 to 28,000.
- Now drops the Mechanical Battery Piece in Expert Mode.
- Now drops Skeletron Prime Mask.
- Fixed a bug where destroying the Prime Cannon killed Skeletron Prime.
- Increased health of all Prime limbs.
- No longer spawns during Pumpkin Moon.
- Can now sometimes spawn arbitrarily at night after defeating the Wall of Flesh, indicated by receiving the message "You feel the air getting colder around you..." at dusk.
- Now drops Skeletron Prime Trophy.
- Reduced health of all Prime limbs and head.
- Added to the game.