Roiling Horror

Roiling Horror's power and toughness are each equal to your life total minus the life total of an opponent with the most life. Suspend X—{X}{B}{B}{B}. X can't be 0. (Rather than cast this card from your hand, you may pay {X}{B}{B}{B} and exile it with X time counters on it. At the beginning of your upkeep, remove a

time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.) Whenever a time counter is removed from this card while it's exiled, target player loses 1 life and you gain 1 life.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6oq760jbcvpb1hkk34o2xl.