Ulamog - Mana-Draining

Ulamog reached out with its tentacled bulk, grasped a quantity of earth, and then, horribly, began to drag itself forward. The sound of Ulamog's locomotion chilled Jace's soul—it was the sound of living earth having all its essence leeched out of it, of fierce and wild mana being silenced forever, of rich terrain turning to desiccated bone.

THE BELIEVERS' PILGRIMAGE