even elins gun does't do that great a damage.. if i remember right, draculas are 9200hp each and probably hit around 400hp when i was at lev50, arrow rain is fine if its really strong damage... i.e. real strong atk and top range bow, but you need people who can bind/freeze the bats as well as survive and heal party but you need the powerful hits too, a group of many or 3lev75+ might get you through depending on their stat build