Etherial Skull

Etherial Skull is an Expert Mode-exclusive accessory dropped from Skeletron when defeated in the Etherial Dimension. While in the Etherial, taking damage from any source grants the player the Ether Bones buff for 10 seconds, which boosts all weapon damage by the percentage of the damage the player took to their total health. If the player takes damage again while the buff is active, the buff is reapplied and the additional boost is added to the current boost. The increase in damage cannot exceed 100%.