Fountain Flagstones
Land (Rare)

At the beginning of your end step, if you didn't cast any spells this turn, Fountain Flagstones deals 1 damage to you.

Tap: Add W or U to your mana pool.

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

Lars Critchlow