Blood-Toll Baron

Whenever a non-Vampire creature enters the battlefield or attacks you, put a -1/-1 counter on
it and create a Blood token. (It's an artifact with
"{1}, {t}, Discard a card, Sacrifice this artifact:
Draw a card.")
{1}{b}, Sacrifice another creature or two Blood
tokens: Double the number of -1/-1 counters
on target creature.