"Battle through a labyrinth filled with monsters, marvels, and many other three-player enemy squads as you search for Roshan's rarest cheese and work to be the last team standing," the website says. "You'll need to navigate carefully to earn the XP and Gold needed to destroy your opponents." But there's more: The labyrinth you're in appears to be unstable and there will be cave-ins along the way, limiting the field of play.
As PC Gamer points out, this isn't an exact description of a battle royale, but there certainly are a lot of similarities. It makes sense; these types of games are incredibly popular right now, so why wouldn't others want to jump on the bandwagon and ride it out? We'll likely get more details about The Underhollow, including an available date, soon.