Meta Knight (SSB4)/Up aerial
Meta Knight slashes above himself in an arc. With quick start-up, low ending lag, weak knockback, and deceptive reach, this move is an essential element of his meta game, as it is a centerpiece of his powerful combo ability. It combos reliably off of his dash attack, up tilt, down throw, and forward throw until mid-percents. From low- to mid-percents, it chains into itself and any other aerial, Mach Tornado, and Shuttle Loop. Meta Knight's most well-known combo involves chaining his up aerial into itself repeatedly, and finishing off with a high-altitude Shuttle Loop, KOing at roughly 60%. At higher percents, it can still lead into Shuttle Loop for a KO.
The move's speed gives it good utility against opponents shielding on platforms. Two up aerials followed by Mach Tornado will often result in a shield-poke.