Aurum

"A foreboding chill blankets the world around you..."

Aurum
Aurum is an alternate boss to Skeletron Prime, being summoned with the same item, (the Mechanical Skull), but under different circumstances.

Aurum will only be summoned on a Blood Moon, and only if the summoner is stood on top of gold bricks. Any quantity will suffice as long as they are placed directly below them.

Aurum will also spawn naturally if neither it nor Skeletron Prime have been defeated previously, with a 40% chance to spawn on a Blood Moon. It will flee upon dawn regardless of spawn method.

Stats

 * 16,000
 * 54 Attack, (Contact)
 * 20 Defense

Attacks
Aurum is unlike Skeletron Prime in that it only has two variations of its hands, and they will switch among themselves at will.

Fighting Hands
The fighting hands are melee attackers, actively gliding towards the player in an attempt to attack them. They may also wind up and charge the player in a deadly dash, dealing additional damage. When they reach low health they may become Casting Hands and switch places with previously existing Casting Hands, which become Fighting Hands.
 * 8,000
 * 40 Defense
 * 52 Damage (Contact)
 * 62 Damage (Charging)

Casting Hands
The casting hands behave as ranged attackers, firing multiple types of deadly projectiles from afar. They will attempt to avoid the player, and will not switch places with the Fighting Hands on their own. They will throw bouncing fireballs that will ricochet off surfaces twice and then explode. The fireballs will also explode prematurely if they come in contact with a player. The casting hands also will fire lightning bolts, with the casters now pursuing the player, one floating by their left side and the other to the right. They will pause to fire a lightning bolt to each other, dealing massive damage but allowing a brief margin for the player to escape.
 * 8,000
 * 25 Defense (Normal)
 * 35 Defense (Casting Lighting)
 * 52 Damage (Contact)
 * 60 Damage (Direct Fireball hit)
 * 40 Damage (Fireball Explosion)
 * 75 Damage (Lightning)

Aurum Head
The skull of Aurum will float above the player allowing its hands to harass their target. It will periodically shoot twin lasers from its eye sockets, but will not directly attack the player until two of its hands have been destroyed.

Once two of its hands are destroyed, Aurum's defense will drop and it will now attack ferociously, charging wildly and firing complex patterns of lasers in all sorts of directions. When a third or fourth hand is defeated Aurum will fill in for the duties of its lost hands, mimicking the attacks of its fallen. It will charge and glide at the player if it has lost its Fighter Hands and will launch fireballs and temporarily duplicate itself to chain lightning. The duplicate is invincible and will phase out of existence once the attack is completed.
 * 16,000
 * 40 Defense
 * 50 Defense (Casting Lightning)
 * 52 Damage (Contact)
 * 62 Damage (Charging)
 * 60 Damage (Direct Fireball hit)
 * 40 Damage (Fireball Explosion)
 * 75 Damage (Lightning)

Loot
Upon Aurum's death it will drop the following:
 * 18 Gold Coins
 * 25-45 Souls of Fright
 * 8-18 Greater Healing Potions
 * 25-35 Hallowed Bars
 * 1 Mechanical Battery Piece (Expert Mode)
 * 50% Hand of Aurum
 * 50% Fist of Aurum (Will not drop both)