Adamant Gengar

Evolve Haunter {b}{b}{b} ({b}{b}{b}, Exile a Haunter
you control: Put this card onto the battlefield from your
hand. Gengar gets X +1/+1 counters, where X is the
exiled creatures power. Evolve only as a sorcery.)
At the beginning of your upkeep, each opponent
loses 1 life and you gain 1 life.
At the beginning of your draw step, draw an
additional card.