Lake Flats
Land (Rare)

Lake Flats enters the battlefield tapped unless you reveal a basic land card from your hand.

Tap: Add W or U to your mana pool.

Sacrifice Lake Flats: Add W or U to your mana pool.

WU: Lake Flats becomes a 2/1 blue and white Wizard creature until end of turn. It's still a land.

Justin Prescott