Shadowheart Grove

Shadowheart Grove enters the battlefield tapped.
{t}: Add {b} or {g} to your mana pool.
{2}{b}{g}: Until end of turn, Shadowheart Grove becomes a 3/3 black and green Elemental creature with reach and "Sacrifice a land: Shadowheart Grove gets +3/+3 until end of turn." It's still a land.