It was first seen on videos from E for All before appearing on the DOJO!!!. When used, Meta Knight swings his cape out directly in front of him while shouting either "Know my power!" (思い知れ!, You shall realize!) or "Behold...." (見るがいい!!, Behold!!). If he misses with his cape, Meta Knight pauses for a brief time, and the Final Smash fails. When it connects (the trapping hitbox is a bit longer than the edge of the cape), characters trapped by Meta Knight's cape become invincible, but trapped at the spot where they were caught by the hitbox. The screen then darkens to black, and after a few seconds, a large, single slash appears near Meta Knight, as he then slices the trapped opponents with one, powerful strike. When Meta Knight slashes, he either swings upward or performs a standard slash, though this does not affect the attack's strength.
Characters who are trapped by Meta Knight's cape always receive 40% damage, and high, upwards knockback that can KO above 50%, with super armor ignored. Any opponents who are not trapped are also attacked, but instead take about half damage and weak, upwards knockback, with the opponents being hit in player order. Unusually, these slashes can hurt allies as well, even with Friendly Fire disabled; even more unusually, these slashes disregard super armor, making moves with launch resistance ineffective for defense. The weaker slash part of Galaxia Darkness can be avoided by dodging with correct timing. This is a bit harder when playing online with anyone due to players having different player numbers.
The move returns in SSB4 with a starry sky graphical effect applied to the inside of Meta Knight's cape. It also no longer affects teammates with Team Attack off.
Galaxia is the name of Meta Knight's sword in the anime, Kirby: Right Back at Ya!. A legendary sword with immense power, it appears to be a mere hilt when sheathed, with the blade forming after being drawn. The multi-pronged design first appeared in the games with Kirby Air Ride, where Meta Knight used it in his first playable appearance. At the time of Brawl's release, however, it had never been referred to as "Galaxia" in the games. Kirby's Epic Yarn, released after Brawl, is the first game to name the sword "Galaxia". The move itself is named after the sword, while the darkness is created through his Dimensional Cape.
The actual attack appears in Kirby: Planet Robobot, as part of Meta Knight's moveset. It visually resembles his Final Smash, only with a horizontal strike as opposed to a diagonal one.
Meta Knight's Final Smash. He flips his cape, and the darkness within envelops his foes and plunges the world into shadow. He then unleashes a series of sword strikes that do terrible damage and launch his foes. In the darkness, Meta Knight can also reach and attack distant enemies. One can imagine Meta Knight zipping back and forth at high speed to accomplish this.
Spring lag glitch
The spring lag glitch is a glitch in Super Smash Bros. Brawl which causes a character hit by Meta Knight's Final Smash to get characters frozen on a spring for a short time. As such, this glitch can only be performed on stages that have springs, like PictoChat and custom stages.
To execute this glitch, Meta Knight must break a Smash Ball and use Galaxia Darkness to hit the opponent into a spring. The character that was hit should be stuck in the spring until the duration of Meta Knight's Final Smash is over.