Swamp Battlefield
Land-Swamp Mountain (Rare)

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

When Swamp Battlefield enters the battlefield, you lose 1 life unless you reveal a Red card from your hand.

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

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

James Chan