Juri, of the Juri Revue

Haste, Unleash (You may have this creature enter the battlefield with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)
When a creature you control enters the battlefield with exactly one +1/+1 counter on it, put an additional +1/+1 counter on it.
"Welcome, welcome one and all, to the Juri Revue... Let the bloodshed begin!"