Emil's Ain Soph Aur secret Arte
After the Unison Bar is full, press B to do a Mystic Arte using Emil after using an Arcane Arte. Note: Emil must be in Ratatosk mode. Then, press B again before his Mystic Arte finishes, which is after his face's picture appears, to execute the Ain Soph Aur secret Arte. This is a Light elemental attack.