Mudslide is a rare Enchantment card from Ice Age (ICE), collector number 204. Current market price: $6.71, TCGplayer market prices via Scryfall.
Creatures without flying don't 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.