Rootwater-land
Land (Rare)

Rootwater-land enters the battlefield tapped.

Tap: Add W or U to your mana pool.

Put Rootwater-land on top of your library: Add 1 to your mana pool.

1W: Rootwater-land becomes a 0/4 white and blue Illusion Merfolk creature with defender until end of turn. It's still a land.

Aleksi Briclot