Hold up, to jump in the air (No directional jump) and punch.
With this, it will cause your opponent to bounce up, straight in the air (for an air juggle), allowing you to continue a combo or position
yo subzero's alt version called "cryomancer" where he's summoning sledgehammers looks sooooo serious. he even has midscreen air juggles with the ice sword and that x-ray... lord have mercy this game is too hype