Team RWBY -- circa between volumes 2 and 3 -- end up in the world of Terraria, where they must survive and face eldritch horrors as they fulfil an ancient prophecy and search for a way back home.
The will of a dying world full of Corruption reaches out to another world that, like itself, is a remnant of what it once was. In doing so, it pulls from the other world a group of four warriors in a last bid attempt to save itself from destruction and restore the balance it once possessed. Hijinks ensue.