The Book of the Ancient Ones

{1}, Discard a card: Target opponent discards a
card. Put a page counter on The Book of the
Ancient Ones.
Remove all page counters from The Book of the
Ancient Ones: Exile target creature with mana
value less than or equal to the number of page
counters removed this way.
"Live without regrets."
— Ninomae Ina'nis