The Coronavirus

When The Coronavirus Enters The Battlfield Put A -1-1 Counter On A Creature You Control
Whenever A Creature You Control With A -1-1 Counter On It Deals Damage To A Creature An Opponent Controls Put A -1-1 On It
Whenever You Put A -1-1 Counter On A Creature, Put That Many Plus The Amount Of Creatures With A -1-1 Counter Onto It.