Reef Wreckage
Land (Rare)

Reef Wreckage enters the battlefield tapped unless you control one or more creatures.

Tap: Add U to your mana pool. If you played a land this turn, Add B to your mana pool instead.

UB: Reef Wreckage becomes a 2/1 blue and black Fish creature until end of turn. It's still a land.

Aleksi Nielsen