Stars from six of Nickelodeon’s hit live-action series converge in one special crossover event titled When Worlds Collide, premiering Thursday, April 21, at 7 p.m. (ET/PT) as part of Side Hustle on Nickelodeon. In the event, Henry Danger villain Frankini (Frankie Grande) tracks a powerful mind-controlling device to Altoonisburg, with the goal of world domination. …