Grand Epiphany

Each opponent reveals 3 cards from their hand.
Anytime they cast one of the revealed cards, you
may pay X to counter it where X is the target spell's
mana cost.
"Bad night to be outdoors."
—Thoros
"You've got real powerful magic to figure that out.
Did the Lord of Light whisper that in your ear? 'It's snowing, Thoros. It's windy. It's gonna be a cold
night.'"
—Sandor Clegane