Desert Ruins of Al-Hazaharred

Each land is a desert in addition to its other land type and has "{t}: Add {c} to your mana pool."
{t}: Tap target desert and put an hourglass counter on it. Add {c} to your mana pool.
If a land with an hourglass counter on it would untap during its controller's untap step, its controller removes an hourglass counter from it instead.