From Wiki: "A succubus is a demon in female form or supernatural entity in folklore (traced back to medieval legend) that appears in dreams and takes the form of a woman in order to seduce men, usually through sexual activity. The male counterpart is the incubus. Religious traditions hold that repeated sexual activity with a succubus may result in the deterioration of health or even death.
In modern representations, a succubus may or may not appear in dreams and is often depicted as a highly attractive seductress or enchantress; whereas, in the past, succubi were generally depicted as frightening and demonic."
So looking at the current pic I can imagine what she is doing...she looks rather "horny" to me