Flagstones Vents
Land (Rare)

Flagstones Vents enters the battlefield tapped unless you control two or more colorless permanents.

Tap: Add W or U to your mana pool.

Put Flagstones Vents on top of your library: Add 1 to your mana pool.

W, Tap: Flagstones Vents deals 1 damage to target attacking creature.

Steve Guay