It is said to be a practice that is a particular fringe skill of Necromancy. It is focussed on aiding the necromancer to survive the ordeals of coming in contact with death essences. Instead of simply locking down and bearing the ill effects of death magic, Vampiric magick was born to shoulder some of this responsibility, thus allowing a degree of rejuvenation to coexist with the effects of necromancy.
Necromancers have refined the ability to use death magick to drain from the life forces of others. The precise means of doing this is up to the caster to discover but, through absorption of the life force of other creatures, the necromancer can waylay many of the adverse effects of their art and retain a relatively normal degree of health and well-being at the expense of others.
Though there is no proof that this kind of magic can actually extend the life beyond the normal duration, it has shown that the power to counteract the negative effects of using death magick and thus allows the practitioner to function normally.
Direct Energy Vampirism is probably the most commonly practiced technique of Vampiric magick also known as psychic vampirism. Energy vampirism can be performed via a servitor, in dreams, or by targeting a specific type of energy (sexual energy, the energy produced by religious fervor, the energy produced by some disease or illness - used for healing - or others).
Sexual Vampirism is another form of energy vampirism but typically practiced by those who have refined their tastes to prefer energy released through sex. While vampires are more often than not portrayed as dominant beings, sexual vampirism can be carried out equally well from a position of submission.
Reversed Energy Vampirism is one of the very few uses of energy vampirism I have come across that is actually intended to be beneficial to someone other than the vampire. It is simply a reversal of the feeding process. Rather than pulling energy from the subject and into oneself, the vampire pushes energy from himself into the subject. Initially, a visualization of occurring can help as a focus for the donor vampire, as can pooling the energy into one part of the body and from there transferring the energy onto the subject.
Vampiric magick also includes a degree of working with entities like incubi and succubi, as well as various deities. Some form of blood magick falls under this description, as do rites which are designed to endow certain properties of the vampire upon the operator.
Practitioners of Vampiric magick, although many have an affinity with the vampire archetype, generally don't feel that they have some innate need for energy or blood which must be fulfilled. They instead take up Vampiric practices by choice, and often for a specific reason.
ii-wy em Hotep - Patrick Gaffiero