Drawing upon many sources Kaleiman briefs you (this is the DM's way for giving out some key information):
"Vampires are undead. They have little in common with men, save in outer resemblance. In reality they do not eat, breathe, tire or require sleep. These are characteristics that they share with all undead creatures. Here most similarities end, however, for vampires are far...superior to any other undead in terms of abilities...and perhaps most importantly, mental faculties. For example, it is apparent that they have supernatural senses - they can see things in the dark, hear a heart bating at a hundred paces, and smell blood a mile away.
They do require some sustenance, however. They crave human life. Preferably by first enthralling a human victim and then feeding of his blood at their leisure. That would seem their preferred method of 'feeding'. They even have specialized retractable fangs to facilitate this feat. But as has been reported; a vampire CAN steel a person's life just by touching him. I even have accounts, but not substantiated one, of vampires draining away life at a distance. I do not know how often or how much a vampire needs to feed. But I do suspect that a well-fed vampire is somehow stronger and more vigorous than a hungry one. And that a vampire who actively uses some of its 'gifts' somehow consumes its stolen life energy, like a man would grow tired from strenuous activity.
Vampires a physically challenging opponents. They are superhumanly strong and fast. I have reliable accounts of seemingly plain-looking vampires thrown armored men or punching bare-handed through heavy armor. And vampires can run as fast as any horse, perhaps faster. Yet it should be noted that a vampire does not automatically become a skilled warrior. If it was a commoner in life it will remain a commoner in death...only a very strong and fast commoner. They have fangs with which to bite...but I think they usually reserve them for feeding. I've also plenty of accounts of vampires having - or growing - wicked claws. Not sure if that is universal though. Some may only fight with weapons or their bare hands.
Their undead state also makes them immune to many kinds of damage. A sword strike to the vitals will kill a man - but not a vampire, since it has no vital organs. In addition it would seem that vampires are unusually robust, in that hacking a vampire to pieces or crushing its bones requires considerably more force than it would a normal man. Silvered weapons are reported to be more effective against vampires than normal weapons. I believe this to be true - but remember my previous comment holds true, even with a silvered weapon you must hack the vampire to pieces before it dies. A strike to the vitals will not work. Two exceptions; hack of its head and it dies, but then again that kills almost anything...and pierce in the heart and it is rendered immobile. Any weapon will do for that I think. The wooden stake is just a tale - a steel or silvered sword will do equally well. Though I have not actually tested it.
When it comes to the magical arts it is my belief that vampires retain the abilities they had in life. Perhaps they are even stronger. Adaliz bint Daouta certainly was surprisingly capable. And we know for a fact that the Grey Duke himself is a powerful sorcerer that is capable of realm magic...although thankfully his sources are not of THIS world. I wold not know if a person with priestly powers would somehow retain them...perhaps by pledging his soul to darkness. There is nothing in the sources regarding that.
Vampires are not invulnerable. As undead they fear light, especially the light of Avanalae. They are active at night and generally seem to rest during the day, though I do not want to say that they CANNOT move in the daytime. I'd rather say it would be more like a normal person trying to stay up throughout the NIGHT, but perhaps even more tiring. Direct sunlight do them harm - prolonged exposure to bright and pure sunlight will burn a vampire into ash, but even bright magical light should do them harm. On an overcast day or wearing heavy clothes I think they would only be greatly discomforted, but I do not think it would kill them. Oh, and bright flares of light might effectively blind them, for some time at least, but remember they have other, superhuman senses as well. Fire would appear effective as well. The cleansing fire of Avanalae's daughter Laerme will burn them as sunlight does, and can be used to put a vampire to final rest. Torches, bruing oil..magic spell...they are equally effective, and might be one of our best weapons...
There is more, but I will leave the floor open for comments...
