Permafrost Trap WWK/34

Set: Worldwake
Collector Code: WWK/34
Name: Permafrost Trap
Type: Instant — Trap
Oracle text: If an opponent had a green creature enter the battlefield under their control this turn, you may pay {U} rather than pay this spell's mana cost. Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Rarity: Uncommon