Aether

Aether is a special skill that can be used by Ike from the Fire Emblem series in Super Smash Bros. Brawl. Although its use in Super Smash Bros. Brawl is unknown, it is said to be able to instantly knockout someone with a single stroke. However, in the game Fire Emblem: Path of Radiance, it does not instantly knockout someone but instead gives an opponent heavy damage and recovers health equal to half of that damage. This could also possibly be Ike's Final Smash move.