Rot Fortress
Land (Rare)

When Rot Fortress enters the battlefield, sacrifice it unless you pay W.

Tap: Add B to your mana pool. Activate this ability only if you control a Swamp.

Tap: Add W to your mana pool. Activate this ability only if you control a Plains.

Tap: Prevent the next 1 damage that would be dealt to target creature this turn.

Greg Grant West