One of the Super Abilities used by Kirby in Kirby's Return to Dream Land and its remake.
It also appears in the Super Smash Bros. series as a Final Smash.
It allows Kirby to use a large sword or a similar object to defeat enemies and destroy certain parts of the terrain.
Magolor can use his own version of it in Kirby: Star Allies, as well as when he finishes off the Master Crown in the Magolor Epilogue
Multiple variations can appear:
This tag implicates sword_kirby (learn more).