Drowned Stronghold
Land-Island Swamp (Rare)

(Tap: Add U or B to your mana pool.)

When Drowned Stronghold enters the battlefield, sacrifice it unless you pay B.

2, Tap: Target land becomes a 3/3 blue Faerie creature until end of turn. It's still a land.

Tap, Sacrifice a Swamp: Add BB to your mana pool.

Christopher Grant West