When Tranquil Cairns enters the battlefield, sacrifice it unless you pay .

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

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

: Tranquil Cairns becomes a 0/4 white and black Kor Soldier creature with defender until end of turn. It's still a land.