Obsidian-land
Land-Plains Swamp (Rare)

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

When Obsidian-land enters the battlefield, sacrifice it unless you pay W.

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

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

Jason Schuler