Mass Destruction

 is a hardmode staff which shoots giant lasers from the sky, it is dropped by Seth.

Trivia

 * Its name is a reference to the game Persona 3 and one of its music tracks — Mass Destruction which is composed by Shoji Meguro and has vocals sung by Lotus Juice and Yumi Kawamura.
 * Its tooltip refers to catchphrase from 2007 anime series Tengen Toppa Gurren Lagann.