Guide:Skeletron Prime strategies

Type	Boss
Environment	Surface + Night Space + Night
AI Type	Skeletron Prime Head AI
Damage	47/79/119; 94158238 (while spinning)
Max Life	28000/42000/53550
Defense	24; 48 (while spinning)
KB Resist	100%
Immune to
Coins	1230
Hurt
Killed
Entering spinning phase

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"The air is getting colder around you..."

Skeletron Prime is the Hardmode version of Skeletron. It is one of the three Mechanical bosses, alongside The Destroyer and The Twins. It can deal a lot of damage with its four limbs, and its high health and defense allow it to take a lot of punishment. The limbs have the added effect of blocking non-piercing shots aimed at its head.

Spawning Conditions

Skeletron Prime can be spawned by fulfilling any of these conditions:

After smashing a Demon/Crimson Altar, it will have a 10% chance of appearing when night falls, until it is defeated for the first time. This condition is shared with the rest of the trio, so there's a chance that the Destroyer or Twins will spawn instead.
Use a Mechanical Skull at night.

Either way, it must then be defeated before all involved players die, or before daybreak, whichever comes first.

The Fight

Skeletron Prime is a flying boss that consists of five parts:

Prime Saw, a melee arm, with 9000 health.
Prime Vice, a melee arm, with 9000 health.
Prime Laser, a ranged arm that fires lasers, with 6000 health.
Prime Cannon, a ranged arm that fires grenades, with 7000 health.
Skeletron Prime, the head, with 28000 health.

Killing the head will count as a victory, and any remaining limbs will be destroyed.

Each limb has a unique attack pattern, listed below. Although killing the limbs is not necessary, they can block attacks to the head (especially Prime Saw and Prime Vice), and destroying them makes the fight much easier. It is safest to take out the most dangerous limbs at the beginning, as the fight gets significantly easier without their interference.

Prime Saw

Prime Saw is one of the two melee limbs. It lunges at the player, dealing a lot of damage if its attack connects. However, compared to the other limbs, the Saw is not as aggressive, and has a predictable pattern. Accordingly, it is a lesser threat despite the high damage, and a low priority.

Prime Vice

Prime Vice is one of the two melee limbs. Compared to the Saw, it does less damage, but it is more aggressive. It lunges at the player, attacking many times before retracting.

Although its pattern can be somewhat predictable, its behavior when Prime is enraged makes it a very dangerous limb, capable of dealing significant damage if the player is not careful.

Prime Laser

Prime Laser is one of the ranged limbs. It will consistently remain above the player, firing lasers at a moderate rate. Its shots deal significant damage and it is Prime's most threatening limb in Expert mode. The laser starts shooting much faster when Prime enters its "enraged" state, making it an even bigger problem.

Its damaging, fast, and accurate shots arguably make it Prime's most dangerous limb. Because of this and its relatively low health, it should ideally be destroyed before the others.

Prime Cannon

Prime Cannon is the other ranged limb. It shoots bombs that do not destroy tiles or deal contact damage. The bombs also do not collide with platforms. This means that if the player fights in an arena, the Cannon will very rarely do any damage since the bombs only explode when they land on a solid block.(note: if you destroy every second tile of the platform to save up platform blocks, the platform will be considered a solid block and the bombs will explode upon contact)

The inaccuracy and relatively low damage of the bombs makes the Cannon significantly less threatening than any of the other limbs. It can safely be ignored in favor of more dangerous targets.

However, it is important to note that on the hidden seed "For the Worthy", the bombs that the Prime Cannon shoots WILL destroy tiles. Failure to destroy this limb early could result in any arena prepared to be wrecked, making the fight much more difficult.

Skeletron Prime

Skeletron Prime "proper" is the head, which must be destroyed to win. Skeletron Prime will try to float above the player at all times. It will close in to do its spinning attack, which doubles its attack and defense and empowers its other limbs, making them attack more frequently. Once it finishes spinning, it will retreat again.

Like Skeletron, if the head is not destroyed by morning, it will be locked in its spinning attack, gain a speed increase, and its attack and defense will increase to near-unbeatable levels. In this state, a single hit will kill the player, while the head will only take one damage per hit and two damage per critical hit.

Killing the head is a lot easier once some of its limbs are down, especially the Vice and the Laser. Focusing only on the head still works should the player wish to end the fight as soon as possible, but usually it is safer to focus on the arms first.

General Strategies

General tips

This content is transcluded from Guide:Practical Tips § Combat.

For nocturnal bosses, starting the battle just after the sun sets (7:30 PM) will provide the maximum amount of time to defeat the boss. In Hardmode, the Moon Charm and/or Moon Stone and their upgrades are also useful at night.
Boss battles can be won or lost before the battle ever starts. Choose your equipment and have it ready; find and/or make potions and placed buffs; use the highest-tier food you have available; set up an arena appropriate to the boss; learn the strategies for the boss you're facing.
Prepare your Boss-fighting arena with adequate lighting, Campfires and Heart Lanterns for health regeneration, and Stars in Bottles for mana regeneration if you use magic. Bast Statues will provide a significant defensive boost. Garden Gnomes and (if underground) proper torch placement will reduce damage taken and increase damage dealt due to the luck. Note Torch God's Favor helps with this. Honey pools can also be used for extra health regeneration.
Sunflowers provide the Happy! buff to players within a 50-tile radius, which grants a +10% movement speed bonus and 17% reduction in enemy spawn rate.
Always carry around a stack of the highest-tier healing potion available, as relying only on natural Health Regeneration is not a good idea. Depending on the game stage, this can include items such as Mushrooms or Honeyfins. On the PC, Console, Mobile, and tModLoader versions, Restoration Potions are healing potions with a shorter cooldown.
- Likewise carry mana potions, if you use Magic.
- The Strange Brew is also an option, but its weak healing effect will trigger the Potion Sickness cooldown as well as Mana Sickness. On the Old-gen console version, Windows Phone version, Old Chinese version, Nintendo 3DS version, and tModLoader 1.3-Legacy version, Restoration Potions can save a slot, but will likewise trigger both cooldowns.
It is suggested to build houses for the Dryad and the Nurse NPCs in your arena. The former casts the Dryad's Blessing buff, which increases your defense and provides you with a thorns-like effect, while the latter can heal and remove debuffs instantly, at the cost of some coins.
Bosses are displayed on the Minimap: Follow the boss's icon to track it when you're struggling to find it. You can identify the boss icons by checking their respective wiki pages.
Once you have freed the Mechanic in the Dungeon, you can use Wire to enhance your arena with Traps and helpful Heart and Star Statues. The former helps to damage the enemies, though be careful to set them up correctly in order not to hurt yourself during the battle. The latter will spawn heart and star pickups, respectively. Connect these devices to timers.
It may be useful to summon and kill the Eye of Cthulhu or King Slime before summoning any harder boss in order to spawn an extra one-use pool of Hearts. Note that this will prevent any Heart Statues from spawning new Hearts.
Remember to use the Sharpening Station, Ammo Box, Crystal Ball, Bewitching Table, and Slice of Cake before you go to explore or battle bosses/invasions. These will give boosts that are useful to take, with the first four being class-specific. They give Sharpened, Ammo Box, Clairvoyance, Bewitched, and Sugar Rush, respectively.

Terrain preparation

As with all bosses, an arena made out of Wooden Platform or Minecart Track greatly increases your mobility, and it will also moot the Prime Cannon. You will want several rows of Platforms, each around 50 or so blocks long. The platforms should be suspended off the ground to prevent the Prime Cannon's grenades from detonating too close to you. A solid ceiling should be avoided since Skeletron Prime will often retreat a fair distance when not using his spinning attack.

Gearing up

Armor

Adamantite armor provides the overall greatest increase to all stats.
Titanium armor is a great choice due to its high stats. It also provides different buffs, depending on which version you play on: Shadow Dodgeon pre-1.4 and Titanium Barrier on 1.4.
Crystal Assassin armor's respectable defense and stat boosts can make it a viable alternative to Hardmode ore sets.
Orichalcum armor provides very high critical strike chance and its set bonus can hit multiple parts.
Palladium armor provides lower stat bonuses, but the Rapid Healing greatly increases natural regeneration.
Hallowed armor becomes a great choice if you have already defeated a Mechanical Boss, since it provides the Holy Protection buff on Desktop version.
Spider armor is the best choice for Summoners.
The armor sets available from the Tavernkeep combine summoning with one of the other classes. This is only available if you've already defeated one Mechanical Boss.
Frost armor and Forbidden armor provide weak stat bonuses, but allow you to mix different damage types.

Weapons

For melee users

The Hel-Fire, Amarok, or Yelets with the Yoyo Bag are all very strong choices.
The Shadowflame Knife is also a very good choice. Its bouncing properties allow it to hit multiple parts of its body at once.
The Ice Sickle fires a spinning scythe projectile that will hit Skeletron Prime multiple times.
The Dao of Pow does heavy damage to Skeletron Prime or its arms if aimed well. It's much less on pre-1.4 versions, however.
After a Mechanical Boss has been defeated, the Death Sickle can be used.
Once you have defeated The Destroyer, Light Discs can be very helpful with their long range.
If you manage to acquire them, Bananarangs are a very effective weapon, due to their high damage and speed.
The Chain Guillotines can be useful, if you have already beaten a Corrupt Mimic.

For ranged users

The Adamantite Repeater, Titanium Repeater or Star Cannon or if another mechanical boss has already been defeated, the Hallowed Repeater can be easily obtained. Combine them with Holy or Ichor Arrows for high damage.
The Onyx Blaster and Clockwork Assault Rifle are very powerful guns made even stronger with Crystal Bullets.
If you have defeated The Destroyer, the Megashark is a very powerful option due to its insane speed and respectable damage.
The Daedalus Stormbow is extremely powerful - especially when combined with Holy Arrows. If one mechanical boss is defeated, then the Phantom Phoenix with Holy Arrows provides slightly less damage but with better aiming.
The Dart Rifle and Dart Pistol are both very strong with Crystal or Ichor Darts.
It is recommended to use a secondary weapon with Ichor ammo, as the debuff will make Skeletron Prime significantly more vulnerable to damage.

For magic users

You can use the Crystal Serpent which functions similarly to Crystal Bullets and deals high damage.
The Sky Fracture is just as strong.
The Meteor Staff is powerful and easy to craft, provided you have some leftover Meteorite Bars from Pre-Hardmode.
The Golden Shower deals little damage but inflicts the Ichor debuff, allowing your other weapons to deal even more damage.
The Flower of Frost is a decent weapon that inflicts Frostburn, which Skeletron Prime is not immune to.
The Rainbow Rod is available if you have defeated The Twins previously. The projectile is homing and piercing, meaning it is all but guaranteed to hit three sections of the boss with each cast while at the same time allowing you to focus on dodging.
Beating a Hardmode goblin army can provide access to the Shadowflame Hex Doll, dropped by the Goblin Summoner. The scattering attack can hit multiple limbs and the head rapidly, dealing substantial damage in little time.

For summoners

Template:Item/options

If you have already defeated The Twins, you can use the Optic Staff to summon miniature versions of them.
The Spider Staff is very useful for defeating the laser and cannon, as they don't move much and allow the spiders to cling for longer.
The Queen Spider Staff is a great choice if you tend to remain in one area the entire battle.Template:Item/options
Whips, especially the Cool Whipwith it's armor-ignoring snowflake projectile, are effective at dealing damage to several body parts at once or empowering your minions.

Accessories

Accessories that increase your mobility such as the Lightning Boots or Wings are a must.
An Emblem for your class can increase your damage output significantly.
The Frog Leg ( and its upgrades) makes all wings significantly faster, which helps when dodging its attacks.
The Charm of Myths increases your base health regeneration and reduces the cooldown on potions, making it a good choice if you have trouble dodging its attacks.
The Cobalt Shield or its upgrades make you immune to knockback, preventing Skeletron Prime from knocking you around.
The Expert-exclusive Shield of Cthulhu can greatly increase your mobility as well as provide some extra defense.
The Expert-exclusive Worm Scarf will reduce damage taken, making it a powerful choice.
On 1.4, the Expert-exclusive Brain of Confusion has a chance to dodge an attack, providing the player with a useful Cerebral Mindtrick buff.

Potions

Greater Healing Potions are recommended.
You can also use Horn o' plenty if you have beaten Turkor the Ungrateful.
For buff potions, the Swiftness Potion, Ironskin Potion, and Regeneration Potion will help out immensely.
The Endurance Potion will complement the defense boost of the Ironskin Potion.
Rangers with Bows should bring along an Archery Potion or two.
Mages greatly benefit from Mana Regeneration Potions and Magic Power Potions.
Damage increasing potions like the Rage Potion and Wrath Potion are good for everyone.
The Lifeforce Potion increases your max health and allows you to take more hits.
A Summoning Potion will help with extra damage, even non-summoners can benefit from having a summon from something like the Optic Staff.

Mixed Strategies

It is possible to defeat Skeleton Prime by continuous attacks alternating the Megashark and a full stack of Light Disks, while wearing a full set of Palladium armor. However, this is likely to cut the time limit very close, and whichever headpiece you choose, only one of your weapons will get a class bonus. In general, Hardmode fights reward class purity.
It is very easy to defeat Skeletron Prime with The Black Spot, he won't even hurt because it is faster than him. The only thing you need is stable and high enough damage to beat him until dawn.

Tips

When using Summon weapons, it is recommended to use the targeting function to focus one arm at a time and reduce the threat Skeletron Prime poses. Simply right-click near one of the weapons to target it and your minions will prioritize that arm.
All classes should note that Frostburn is one of the few available debuffs that this boss is not immune to, so any weapon providing it or the frost armor will be especially handy. If available, Ichor is also useful to cut into the boss's high defense.
If you want to dodge Skeletron Prime after he does his spin attack, jump normally without wings to dodge attacks, as he comes back if you run away from him while he is doing his spin attack.
Skeletron Prime is overall the best choice as a first mechanical boss kill, as he has much lower damage output than the other two. If properly equipped, the biggest challenge will be ending the fight before dawn.
It is possible to defeat Skeletron Prime during the day, however due to it's high speed and insta-killing head spin, it would require very high speed, (Asphalt Blocks can help) a lot of ammo, patience, excellent mobility, and very good dodging. (Almost Exactly like defeating the Dungeon Guardian, but more dangerous)

↑ ^1.0 ^1.1 Information taken from the PC 1.4.1.2 source code, method AI() in Terraria.NPC.cs (under aiStyle == 32) There may be inaccuracies, as the current PC version is 1.4.4.9.

[headai-1] 1.0 ^1.1 Information taken from the PC 1.4.1.2 source code, method AI() in Terraria.NPC.cs (under aiStyle == 32) There may be inaccuracies, as the current PC version is 1.4.4.9.

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