She worked to condemn human souls to Hell by turning them into witches. She was once a mentor of the demon Ruby while she was human. She created a coven of witches Renee Van Allen, Elizabeth, and Amanda Burns, which resulted in several deaths, including the entire coven.
Tammi later revealed her true colors as Sam was interrogating the coven. She then killed one of the girls and overpowered Sam. Dean then shot her with the Colt. She then stopped the bullet using telekinesis. Ruby then showed up and pretended to want to serve Astaroth. This broke out in a fight and Astaroth overpowered Ruby. Just as she was about to kill Ruby, she was then killed by Dean using Ruby's knife.