Viper

At the beginning of each upkeep, create a 0/1 artifact creature token named Snake Bite with "when this creature dies, target creature gets -1/-1 until end of turn."
Sacrifice two Snake Bites, {t}: Creatures attacking you or planeswalkers you control get -2/-2 until end of turn.
{5}{u}{b},{t}: you get an emblem with "attacking creatures opponents control get -2/-2. Constructs you control get +1/+0 and infect."
You wanted a Villain? I gave you a villain