Cascade Stronghold
Land-Island Swamp (Rare)

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

Cascade Stronghold enters the battlefield tapped unless you sacrifice a land.

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

BB, Tap, Sacrifice Cascade Stronghold: Put a -1/-1 counter on target creature.

Douglas Myrfors