Similar to Monster Hunt and Dungeon Run, Rumble Run is a single-elimination tournament against a series of increasingly difficult opponents. Players will choose from one of three Shrines at the start of each run, each of them dedicated to a Loa—a legendary minion—representing one of Hearthstone's classes.
As you defeat the champions of the other eight teams you'll earn new cards that make you and your team more powerful, but the opposing teams will grow in power as well. The ultimate goal is simple: Beat everyone, be the champ, and score yourself a nice Rumble Runner card back.
You can get a look at all 135 new cards added in Rastakhan Rumble here, and if you'd rather get straight to the good stuff we've got some expert analysis of the expansion's ten most exciting cards. A more detailed look at Rumble Run itself can be had at playhearthstone.com.