The Phyrexian assault on the metallic plane of Mirrodin intensifies. The Mirran resistance rallies to survive and overcome. Both sides bring the full might of their arsenals to bear. The silver golem Karn has retreated to Mirrodin's Core, being worshipped as the new Father of Machines. When Phyrexia grows upon Mirrodin, Karn is trapped in his own mind, battling between himself and the role the Phyrexians are trying to force upon him.
• Each Mirrodin Besieged Booster Pack contains 6 randomly inserted game cards.