The Stairs-to-Slide Charm - Charm cantrip
Casting Time: 1 action
Range: 30 feet
Duration: Concentration, up to 1 minute

Famously used to protect the Hogwarts girls' dormitories from intruders, this spell changes the angle of all connected steps in a single flight of stairs within range. They angle downwards, turning into an abnormally slick ramp.