The Souless are previous clerics of other deities who have flocked to the call of Sethalis (enter Evil God Here) and have chosen to forsake their previous duties and follow Him unerringly. Whether Sethalis came to them, or they began searching for Him, the end result was a deal that took a portion of their soul and left them with powers they had never wielded before.
They will appear usually as they did in life, except for pale skin and gaunt features as their bodies get older. While they do not age, their bodies will in fact begin to slowly die. They augment this by taking in the life essence of their victims. By taking this essence they effectively return that which is lost and rejuvenate their bodies and minds. This essence is not their blood but their lifeforce, their inner spirit. Since the Souless have no souls, they sap the energy from the souls of the living.
If one does not partake in the taking of essence they will literally become a mindless husk frantic on feeding. In their frantic state they usually end up tearing and actually eating their victims, leaving bits and chunks of flesh scattered about. Enough so as to have them die within seconds of the attack. Where the typical Souless only needs the skin pricked to open the body for the transfer of spiritual essence, and while blood is drawn no blood is taken in this exchange. Souless who are in charge of their senses do not care for the taste of blood as it dirties their spirit, they are more interested in the soul that they do not have.
It is instant pleasure and a feeling of highened elation but it is fleeting and never stays more than a few days. The young and strong in spirit usually sustain them the longest. During this draining of essence, they can gain knowledge and memories of their victims.
Their bite is probably the most feared attack that the Souless have. While it may only do minor injury there is a small chance that those bitten will contract a wasting disease and become one of the Damned. The Damned are those who are under the full control of the Souless. This bite is two fold. One is has the ability to turn the bitten into the Damned as stated, but it also drains the Spirit from the target and rejuvenates the Souless, repairing any injuries they may have had. This is also what keeps them mentally intact and rejuvenates their appearance.
The Souless are not injured by the sunlight, but are uncomfortable and have trouble seeing. It causes them no physical pain but they do have a itching discomfort in the back of their mind as if their previous God looks down on them in scorn. Running water, garlic, and silver do no injury to them and does not harbor their passage. Water sanctified by a church will harm them as well has block their path until it dissipates. White ash has been known to give them pause but this has not been verified.
They seem to be vulnerable to holy items, especially those from their previous church. It is apparently their old worshiped God holds contempt for them and has their members try and hunt down the abominations.