Eldisen, the Elder Caves

Eldisen, the Elder Caves enters the battlefield tapped. It doesn't untap during its controller's next untap step after it is put onto the battlefield.
{t}, Exert this land: Add {w}{w}{w}, {w}{w}{u}, {w}{u}{u}, {u}{u}{u}, {u}{u}{r}, {u}{r}{r}, {r}{r}{r}, {r}{r}{w}, or {r}{w}{w} to your mana pool.