Flooded Karoo
Land (Rare)

When Flooded Karoo enters the battlefield, sacrifice it unless you pay W.

Tap: Add WU to your mana pool. Flooded Karoo doesn't untap during your next untap step.

WU: Flooded Karoo becomes a 2/1 blue and white Cephalid creature until end of turn. It's still a land.

Steve Pollack