Dehydration is a common Enchantment — Aura card from Mercadian Masques (MMQ), collector number 73. Current market price: $0.07 (foil $0.77), TCGplayer market prices via Scryfall.
Enchant creature (Target a creature as you cast this. This card enters attached to that creature.) Enchanted creature doesn't untap during its controller's untap step.