Unstable Marsh
Land (Rare)

Unstable Marsh enters the battlefield tapped.

Tap: Add B or R to your mana pool.

Put Unstable Marsh on top of your library: Add 1 to your mana pool.

1R: Unstable Marsh becomes a 1/1 black and red Beast creature with first strike until end of turn. It's still a land.

Douglas Argyle