Mickro, the Afflicter

Mickro, the Afflicter enters the battlefield with
five -1/-1 counters.
Whenever you cast a spell, move a -1/-1 counter
from target creature onto another target creature. Whenever a creature with a -1/-1 counter attacks,
it gains. "This creature deals two damage to any
target."
Creature you control can not be a target of spell
or ability as long it has a -1/-1 counter on it.