Ghostly Mentor

Whenever you gain life and a opponent loses life
in the same turn, you may pay {w/b}{w/b}{w/b}. If you
do, your creatures gain lifelink and deathtouch
until end of turn.
Sacrifice a creature: Your opponents lose 1 life
and you gain 1 life.
Their death to nourish your life. Your life to nourish
our death. And our secrets will be yours.