Professor Putricide

Whenever a Plague token deals damage to a
player, put that many +1/+1 counters on
Professor Putricide.
Whenever a source deals damage to Professor Putricide, create that many Unholy Plague
tokens attached to that source's controller.
Professor Putricide has trample and infect as
long as it has thirteen or more +1/+1 counters
on it.