Voisin, the Blood Witch

Voisin, the Blood Witch has Ward {x}, where X is
equal to the number of -1/-1 counters on
creatures you control.
{b}{b}, {t}: Creatures you control gain persist until
end of turn.
{p/b}{p/b}: Remove a -1/-1 counter from a creature
you control. That creature gains lifelink until end
of turn.