The control-change effect of Piper of the Swarm's last ability lasts indefinitely. It doesn't wear off during the cleanup step, and it doesn't expire if Piper of the Swarm leaves the battlefield. In a multiplayer game, it does expire if you leave the game.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.