A screeching cawing whirlwind of buffeting wings, clawing talons and pecking beaks.
Raven swarms attack by surrounding their prey, pecking, scratching and clawing until destroyed or frightened away. They specifically seek the head, face and eyes of victims.
Any living creature damaged by a raven swarm must succeed on a DC 11 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 a remove blindness or a successful DC 11 Heal check. The save DC is Constitution-based.