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Aether is Ike's up special move, based upon the skill obtainable in Fire Emblem: Path of Radiance, Fire Emblem: Radiant Dawn, and Fire Emblem Awakening. When used, Ike throws his sword up into the air, damaging any nearby enemies, and knocking them into the air, then jumps up, flips, and slams back toward the ground. Ike also gains super armor while throwing his sword, but it only lasts until he jumps, and can be interrupted if Ike gets grabbed. The move offers very little horizontal distance, which can be a hindrance to Ike if he's not below a ledge.
Ike receives two custom special variants for this move in Super Smash Bros. for Nintendo 3DS / Wii U:
The first variant is Aether Drive, where Ike throws his sword diagonally into the air, and slams back down. The move offers better horizontal distance, which helps Ike's recovery, but at the same time, the move's vertical distance is shorter than that of the default Aether.
The second variant is Aether Wave, which creates a shockwave when landing that extends the range of the attack, but does not deal as much damage.