Xenoghast, the Scourge

{t}{1}{b}: put a virus counter on target non-artifact creature.
"Virus Counter for each turn a creature has a virus
counter add -1/-1 counter the beginning of your upkeep"
Whenever a creature with an virus counter
dies create a 1/1 black green horror creature
token with "when this creature dies put an
virus counter on a nontoken nonartifact creature."