Invoke the Vampire Lord

Minimum Spell Level: 8th.

This invocation functions as beast shape IV, except that it allows you to assume the form of a medium bat swarm. You gain a +6 size bonus to your Dexterity, a -4 penalty to your Strength, and a +1 natural armor bonus. You also gain blind sense 20 ft., low-light vision, DR 20/-, and swarm traits. Your swarm attack causes creatures to bleed, losing 5 hit points per round. Multiple wounds do not result in cumulative bleeding loss. The bleeding can be stopped by a DC 10 Heal check or the application of a cure spell or some other healing magic.