Crossover with DC's Legends of Tomorrow. Slight spoilers ahead.

Set during LoT Season 1 sometime before the Time Masters reveal and before the MLP Season 5 finale.

A team had been formed by former Time Master Rip Hunter, an unlikely team, but they wish to prove themselves as Legends. Their mission: stop Vandal Savage before he conquers the world in the future.

After travelling to a point where they believed he could be stopped, Vandal got a hold of an artifact that could travel through dimensions. And so, the Legends follow him, unaware of his location.

With the Waverider in this strange world, the Legends must save this world and theirs from Vandal Savage's tyranny and whatever the Time Masters throw at them to stop them from messing with time and space.