Memnor, Mad Alchemist

Rat Offering (You may cast this card any time you
could cast an instant by sacrificing a Rat and paying
the difference in mana costs between this and the
sacrificed Rat. Mana cost includes color.)
{b/g}{b/g}, {t} Sacrifice a Human and a Rat:
Create a 1/1 black Rat Horror creature token
with Infect and Menace.
"I'll build an acid pit... Then make an army of rat
people..." - Memnor