Fathomless Mud of the Swamp

Vigilance, swampwalk
Nonbasic lands are Swamps.
Creatures without flying do not untap during
their controllers' untap steps.
At the beginning of each player's upkeep, that
player may choose any number of tapped
creatures without flying they control and pay
{2} for each creature chosen this way. If the player
does, untap those creatures.