With the death of Avacyn, the last protections over Innistrad have faded. Nahiri has summoned Emrakul to the plane, to take revenge on Sorin Markov. The Titan of Corruption and Warper of Biology twists all things living, be it plants, animals, or sentient beings, into Eldrazi Horrors. Mutations frequently gain Emrakul's fibrous lattice motif, often including tentacles, extra eyes and limbs and her bizarre colorations. The mutations include five increasing levels of corruption: distorted, disfigured, deformed, misshapen and monstrous. Some of the affected creatures meld together into new organisms. The few unaffected survivors, humans and native monsters alike, fight a losing battle against their mentally and physically twisted former peers. Now Innistrad's fate rests in the hands of unlikely allies: Jace Beleren brings the Gatewatch, and Liliana Vess brings hordes of undead immune to Emrakul's influence.