DC's Legends of Tomorrow S2 E17

When heroes alone are not enough ... the world needs legends. Having seen the future, one he will desperately try to prevent from happening, time-traveling rogue Rip Hunter is tasked with assembling a disparate group of both heroes and villains to confront an unstoppable threat — one in which not only is the planet at stake, but all of time itself. Can this ragtag team defeat an immortal threat unlike anything they have ever known?