Darksteel

"The world . . . is . . . hollow." This is the secret that Chunth, the Tel-Jilad troll elder, entrusts to Glissa Sunseeker before his death at the hands of a traitor. Armed with that knowledge, Glissa fights her way through the great Vedalken capital of Lumengrid, down into the Pool of Knowledge. The Synod's sacred chamber contains a lacuna, a tunnel saturated with blue mana, that leads to Mirrodin's secret interior. There, huge bizarre towers of fungus-like metal called mycosynth reach up toward an immense inner sun of pure mana.