Skeletron Premier

Skeletron Premier is the War Mode upgrade to Skeleton and Skeleton Prime. He is summoned with a Silicon Chip. He has six limbs, each of which has its own attack pattern. He has a laser, a cannon, a gun, a sword, a flail and a saw. Only the head must be destroyed to defeat the boss.

Head

 * 30,000
 * 175 damage (Melee)
 * 190 damage (Head Spin)
 * 50 defense
 * 0 defense (Head Spin)

Laser Arm

 * 8,000
 * 30 damage
 * 30 defense

Cannon Arm

 * 8,000
 * 40 damage
 * 100 damage (Explosion)
 * 35 defense

Gun Arm

 * 6,000
 * 60 damage
 * 70 defense

Sword Arm

 * 10,000
 * 60 damage
 * 50 defense

Flail Arm

 * 9,000
 * 45 damage
 * 50 defense

Saw Arm

 * 8,000
 * 50 damage
 * 45 defense

The Battle

 * The head will stay away from the player most of the time. Rarely, it will start spinning and will attack the player. During the spinning, he summons a force-field that will protect him from all attacks. The forcefield can be destroyed, as it has 2,000 and 50 defense. Once destroyed, Skeleton Premier is open to attack while his head is spinning. He has no defense during this time, so it is a good time to attack him.
 * The Laser Arm will stay away from the player, shooting lasers at them. It is the weakest arm, and is not much of a threat.
 * The Cannon Arm will also stay away from the player, and will shoot cannonballs at them. The cannonballs travel rather slowly and can be easily dodged. When a cannonball hits the ground, it will explode, dealing damage to all players in the explosion radius. The cannonballs travel through wooden platforms, so an arena made out of them is very useful.
 * The Gun Arm will shoot at the player. The bullets travel very fast and are hard to dodge. This arm is extremely strong, but has low health, so destroying this arm makes the battle much easier.
 * The Sword Arm will stay very close to the player, swinging at them often. It is also very strong, so this arm should be destroyed as well.
 * The Flail Arm won't attack very often, but when it does, it swings a huge ball at the player. This arm doesn't do much damage, but has extreme knockback, so avoiding it is recommended.
 * The Saw Arm will often stay out of the way, but when it does attack, it will try to hit the player 3-5 times. It also travels quite fast.

Drops
These items only drop if the respective arm is destroyed during the battle:
 * 5-6
 * 50-100 Mechanical Bones
 * Force Field Generator (20%)
 * Mechanical Laser (50%)
 * Mechanical Cannon (50%)
 * Mechanical Gun (50%)
 * Mechanical Sword (50%)
 * Mechanical Flail (50%)
 * Mechanical Saw (50%)