Donut's spell that violently ejects a rider or parasite from within a host body.
Laundry Day is a spell Princess Donut casts to eject one being lodged inside another. At the climax of the Gasworks Screw Factory heat, with the war-god Grull bearing down to smite Carl, Donut finishes casting Laundry Day and blasts the orc Maestro clean out of the god's chest — revealing that Carl's old enemy had been secretly riding and steering Grull all along. The ejected Maestro drops like a rock into the molten river below; though he can't die on this floor, the hit buys the crew precious minutes before he regenerates.
Donut quips 'we don't have time to kill you now — maybe next time,' turning a defensive escape into an unmasking of the hidden puppeteer.
Donut's ejection spell, used to expel the Maestro from inside the war-god Grull.
Also appears in books you've already read — spoiler-safe to their endings: