Sunken Lowlands
Land (Rare)

Sunken Lowlands enters the battlefield tapped unless you control two or more creatures.

U, Tap: Add WW to your mana pool.

W, Tap: Add UU to your mana pool.

1W: Sunken Lowlands becomes a 0/4 white and blue Crab creature with defender until end of turn. It's still a land.

James Staples