Permafrost Trap | Magic: The Gathering
Formats Permafrost Trap is Legal in
Official Oracle Text for Permafrost Trap
Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Official Rulings for Permafrost Trap
3/1/2010 : If a targeted creature is untapped at the time its controller's next untap step begins, the second part of the ability has no effect on it.
3/1/2010 : If an affected creature changes controllers before its previous controller's next untap step, this ability will prevent it from untapping during its new controller's next untap step.