The end draws near...
Forsaken is an enemy ability used by Kefka in the final battle of the game in the original versions, and also by Omega Weapon in the Advance and iOS/Android versions. It is Kefka's most powerful attack, with a spell power of 220, and deals unblockable non-elemental magic damage to the entire party at the cost of 20 MP. When charging up the attack, Kefka will say, depending on the version, "The end comes... beyond chaos..." or "The end draws near...", followed by an image depicting his laughing head, and then the screen will quake.
Kefka will also use Forsaken as part of his EX Burst, which activates when the button sequence is inputted incorrectly. When using it, he'll ask what his opponent thinks of his attack, and upon using it, will yell "C'mon, c'mon, c'mon!" When about to use it, the camera will zoom up to his face, alluding to how in Final Fantasy VI, Kefka's face was displayed when beginning to charge the attack. In addition, it will zoom back to show Kefka and the opponent in a pose mirroring the final battle from the same game.
Aside from this, he also uses a variant for his standard attack called Forsaken Null.
Forsaken is a moveset used by Kefka in the game as a summon. It turns the background red and causes a purple explosion. As this is going on, Kefka is seen with a contorted face similar to that of his laughing head icon as he's charging up the attack from Final Fantasy VI.
Forsaken means to be "abandoned" or "deserted". In addition, Goner is a slang term meaning someone is about to die (ie, "he's a goner.")