Storm Diver's Additions Mod/Mechanical Spikes

The Mechanical Spikes are an expert-only hardmode accessory that drops from any Mechanical boss treasure bag after all 3 mechs have been defeated. It summons 3 spike balls that orbit the player, each dealing 75 damage and ignoring defense. Additionally most hostile projectiles have a 1 in 7 chance to be destroyed if they enter the radius of the spinning spike balls.

Trivia

 * This was originally going to be a Skeletron Prime expert drop, but it was later made to drop from any of the mechanical bosses.