Artful Attacker

Other Rats you control have a +1/+1.
You may have more than one Artful
Attacker on the battlefield at a time.
As long as you control 5 or more rats, Artful
Attacker has a -1/-1.
{5}{b}{r}: Artful Attacker or another target rat
you control gets a +3/+0 until end of turn.