Millennium Wave (also colloquially called "Millennium Fist") is a super move utilized by Leonardo and Oroku Saki.
The user punches out rapidly at the opponent, and creates after-images of his fists, which act as a short-range projectile. As Leo usually holds his katana in battle, he puts them away before performing the move.
Leo uses the move in the Super NES version of Tournament Fighters. It is Saki's super move in TMNT: Mutant Melee.
Leonardo performs it against a virtual version of Tokka after being transported to a Tournament Fighters-esque game in VR in Deep Trouble!