Consumed by Shadows

As an additional cost to cast Consumed by Shadows, sacrifice a creature.
All black creatures you control gain +3/+2 for five turns. All enemy creatures gain -1/-1.
{b}{b}: All enemy creatures gain -2/-2. If this destroys any creatures, you gain 2 life for every destroyed creature.
"If you gaze for long into an abyss, the abyss gazes also into you."