Bat Form

Dissolve into a bat. You fly very fast, and you see in the dark with a blood-red sonar that outlines every living thing through walls, but your hands are no use in this shape -- except to bite: right-click someone to sink your fangs into their neck (Bat Bite). In a fight, sneak and press the key to change back. Out of combat the shape holds as long as you like, its timer only running down while you fight; there, pressing the key again changes you back and pressing another form's key changes you straight into that one, both for free.