Skeletron Prime

The Skeletron Prime is a hardmode version of the Skeletron boss. It can be summoned with the Mechanical Skull.

Unlike Skeletron it has four hands with different designs and attacks for each. His eyes are red and his mouth has a chomping animation and when he enters the mode where his head spins, his head grows spikes. The blood animation on the normal Skeletron is replaced with fire on Skeletron Prime.

Skeletron Prime can instantly kill after his health drops below 5000.