Negator

Negator is a boss enemy from Final Fantasy X. It is a Machina fought in the Crawler battle at Lake Macalania. The Negator stops the use of magic and summons.

Strategy
During the battle with Crawler, a single Negator may be present. While the Negator is present, magic and aeons are blocked from use; but after its destroyed, the Crawler can charge it's Mana Beam attack. Casting a spell upon the Crawler after a Negator has fallen will summon another Negator.