The Underhollow/Lore

The Underhollow is a tunnel system, deep below Roshan's lair. Heroes fighting the War of the Ancients entered in an attempt to find a wheel of the world's rarest cheese, Roshefort. Noticing the cheese, Roshan the Immortal followed in quickly behind the heroes, leaving them trapped in the labyrinth, scrambling to find that wheel of cheese before Roshan can.