Host of the Cannibrae Sickness

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Creatures with -1/-1 counters on them can't block Host of the Cannibrae Sickness and are Horrors in addition to their other card types.
Horror creatures you control get +1/+1 for each Horror creature on the battlefield.