Astaroth

She was a friend of Renee, Elizabeth and Amanda before she got possessed. It was her who brought the spell book to book club.

Background
She lived in the same neighborhood as her friends and went to book club every month. Then a demon possessed her and she brought a spell book to book club. She is the one who introduced the ladies to witchcraft. So as used the power to help themselves in their everyday lives, she didn't ask for nothing. Nor does she give off the appearance that anything about her has changed.

When Sam and Dean come to investigate, she and Renne come to Elizabeth's rescue. It is believed that it was she who planted the hex bags in the Winchester's room. During a ritual, Sam barges in and reveals that Tammi is in fact a demon (And is already getting what she wants). She flings Sam and reveals that she works for Lilith. She also reveals that Ruby used to be human, and sold her sold to her. Thanks to Elizabeth's distraction, Dean is able to break free and stab Tammi with Ruby's Knife multiple times.

Powers
Strength- Like all demons, she is stronger than normal humans. She is even stonger than Ruby.

Telekensis- She is able to move objects and pin people. She used this ability to pin Sam and Dean.

Wish Granting- Since the coven prayed to her and gave her their souls, she granted their wishes.