X, Cruel Corruptor

({p/r} may be paid with either {r} or 2 life.)
Flying, First Strike, Haste, Menace
X’s power and toughness are both equal to your devotion to black.
{b}{b}{b}{p/b}, Sacrifice a creature: Destroy target
creature an opponent controls. Both players
create a black Nightmare Spirit token, where
each has power and toughness equal to the mana
value of the opposing creature that died through
this ability.