Septic Rats
Septic Rats {1}{B}{B}
Creature - Rat | Power/Toughness: 2 / 2
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Whenever Septic Rats attacks, if defending player is poisoned, it gets +1/+1 until end of turn.
Latest set: [MBS] Mirrodin Besieged ( U · #55 )