A screeching cawing whirlwind of buffeting wings, clawing talons and pecking beaks.
These crows are particularly aggressive, and anyone that enters the building or the nearby yard will find himself beset upon by swarms of angry birds. Once roused, the murder of crows pursues the PCs until they seek shelter in another building. The crows fight to the death.
Any living creature damaged by a murder of crows must succeed on a DC 13 Reflex save or be blinded as the swarm scratches and tears at the victim’s eyes. The blindness lasts for 1d4 days or until healed with remove blindness. The save DC is Constitution-based.