Hecate, Mother of Witches

Coven (This creature gets +1/+1 and has hexproof as
long as you control two or more other creatures that
share a creature type with it.)
Whenever an ability of a curse you control would
trigger, that ability triggers an additional time.
{u}{b}, {t}, pay 2 life: return target warlock from
your graveyard to the battlefield. Activate this
ability only if you control three or more
creatures with coven.