Satana Hellstrom was born a couple years after her brother Daimon. When she was still a child, Victoria discovered her husband and Satana performing a black magic ritual in the basement of their New England mansion. Victoria Hellstrom went mad upon witnessing her husband's transformation and died soon afterwards. Daimon was placed in an orphanage, and Satana was taken to "Hell" to be trained in the use of her demonic powers.
Satana was possessed by a powerful demon called the Basilisk. Satana remained in full control of her mind and body, however, and the Basilisk had to do her bidding when she released it from her body. However, she became aware that the more she used the Basilisk to serve her ends, the stronger it grew, and that it might one day turn against her.
Satana was sent to Earth, where she continually needed to feed on souls. She would often pose as a prostitute to meet her victims.
Her father continued to test her, Satana eventually refusing to serve him. She tried her best to fight other evil forces as well as learn about humans.
Satana learned Doctor Strange had used Shartra's Book of the Damned. His physical body was cursed to be a werewolf, while his astral self was imprisoned by demons. Knowing he was of great importance, Satana freed him and died, as did the Basilisk. 
Years later, Satana was resurrected through unknown means. Doctor Strange asked her, Jennifer Kale, and Topaz to assist him in stopping Hellphyr.
As a succubus, she feeds on the souls of people. Her kiss kills her victims, causing them to shrivel and release the soul in a butterfly like form. Satanna would then capture the butterfly to feed on it. Apparently it does not work on psychic or psionic vampires.
Satanna can release the Basilisk and then return it to her.
She can levitate and possibly fly.
She uses astral projection.
She can fire blasts of hellfire (also known as soulfire).