Writhing Corruption

All creatures get -2/-2. Then gain control of all creatures, they gain haste. Return them to their owners control at the begining of the next end step.
Consumed by a mass of black tentacles and transformed into horrific abominations, the corrupted gain a massive claw like appendage and a new red-eyed serpentine head that resembles both Manus and the Primordial Serpents.