Rot Key
Land-Island Swamp (Rare)

(Tap: Add U or B to your mana pool.)

Rot Key enters the battlefield tapped.

BB, Tap, Sacrifice Rot Key: Put a -1/-1 counter on target creature.

1, Tap: Target land becomes a 2/2 blue Illusion Shapeshifter creature until end of turn. It's still a land.

Jason Spencer