Nabenoch, God of Depletion

As long as your combined devotion to Blue, Red and Green is more than 10, all lands in play gain: whenever this permanent is tapped for mana, it doesn't untap during it's controller's next untap step.
At the beginning of your upkeep add {1} to your mana pool for each tapped land you control.
Mountains crumble and lakes dry in my presence.