Diminish

Diminish is a 6th-level Black Element in. While any party member can equip and use this element, DeadHead, the boss constructed of several Dead Beat, uses this element as an opener when fought aboard the S.S. Invincible.

Description
Cloaking the surrounding area in black, several violet rings appear on the floor, speckled with dark shadows that scurry around and devour the party, temporarily weakening the damage capabilities of all white elements. This element does not weaken White Techs such as Dash&Slash, however.

Name Origin
In English, Diminish means to wan, wither, or weaken in some way. Since the animations show several dark motifs, it only makes sense that it "diminishes" the presence of light, or in this case, white elements.