Guide:Skeletron Prime strategies

"You feel the air 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 /, 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 at night.

Either way, it must then be defeated before all involved players die, and before daybreak.

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, deal contact damage, or 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.

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.

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.

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.

Armor

 * provides the overall greatest increase to all stats.
 * is a great choice due to its high stats and the buff.
 * provides very high critical strike chance and its set bonus can hit multiple parts.
 * provides lower stat bonuses, but the greatly increases natural regeneration.
 * becomes a great choice if you have already defeated a Mechanical Boss.
 * is the best choice for summoners.
 * and provide weak stat bonuses, but allow you to mix different damage types.

For melee users

 * The, , or with the  are all very strong choices.
 * The is also a very good choice. Its bouncing properties allow it to hit multiple parts of its body at once.
 * The fires a spinning scythe projectile that will hit Skeletron Prime multiple times.
 * After a Mechanical Boss has been defeated, the can be used.
 * Once you have defeated The Destroyer, the can be very helpful with their long range.
 * Also, if you manage to acquire them, are a very effective weapon, due to their high damage and speed.

For ranged users

 * The or, or if another mechanical boss has already been defeated, the  can be easily obtained. Combine them with  or  for high damage.
 * The and  are very powerful guns made even stronger with.
 * If you have defeated The Destroyer, the is a very powerful option due to its insane speed and respectable damage.
 * The is extremely powerful - especially when combined with.
 * The and  are both very strong with  or.
 * It is recommended to use a secondary weapon with ammo, as the debuff will make Skeletron Prime significantly more vulnerable to damage.

For magic users

 * You can use the which functions similarly to Crystal Bullets and deals high damage.
 * The is just as strong.
 * The is powerful and easy to craft, provided you have some leftover Meteorite Bars from Pre-Hardmode.
 * The deals little damage but inflicts the  debuff, allowing your other weapons to deal even more damage.
 * The is a decent weapon that inflicts Frostburn, which Skeletron Prime is not immune to.

For summoners

 * If you have already defeated The Twins, you can use the to summon miniature versions of them.
 * The is very useful for defeating the laser and cannon, as they don't move much and allow the spiders to cling for longer.
 * The is a great choice if you tend to remain in one area the entire battle.

Accessories

 * Accessories that increase your mobility such as the or Wings are a must.
 * An Emblem for your class can increase your damage output significantly.
 * The makes all wings significantly faster, which helps when dodging its attacks.
 * The increases your base health regeneration and reduces the cooldown on potions, making it a good choice if you have trouble dodging its attacks.
 * The or its upgrades make you immune to knockback, preventing Skeletron Prime from knocking you around.
 * The Expert-exclusive can greatly increase your mobility as well as provide some extra defense.
 * The Expert-exclusive will reduce damage taken, making it a powerful choice.

Potions

 * are recommended.
 * You can also use if you have beaten.
 * For buff potions, the, , and will help out immensely.
 * The will complement the defense boost of the Ironskin Potion.
 * Rangers with Bows should bring along an or two.
 * Mages greatly benefit from and.
 * Damage increasing potions like the and  are good for everyone.
 * The increases your max health and allows you to take more hits.
 * A will help with extra damage, even non-summoners can benefit from having a summon from something like the.

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.

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 will be especially handy. If available, Ichor is also useful to cut into the boss's high defense.