Mettir, Abyss Abomination

As long as your opponents control no legendary creatures, other Horrors you control get +1/+1.
Whenever a legendary creature an opponent
controls dies, untap all permanents you control.
{2}{b}, {t}: Exile target creature card from a
graveyard. Create a tapped 3/3 black Horror
creature token.
"This hero is now a zero!"