Karles, Master of Puppets

Whenever a non-token creature is put on a graveyard from anywhere, create a 2/2 black zombie creature token.

At the beginning of your end step, you may sacrifice X creatures tokens. Then, return any amount of creatures with total mana cost equal or less than X from your graveyard to the battlefield. Then, put a Toxic 1 Counter
on up to X target creatures.

"I've told you many times. I don't work with corpes, I
work with pathogens... that sometimes come from corpes."