The vampires of the Dwimmermount campaign are based on those of the LBBs, but I've reinterpreted them in various ways, in accordance with the idiosyncrasies of the campaign world, most notably in the fact that one cannot be made a vampire against one's will.
The text in the quote box below is hereby designated Open Game Content via the Open Game License.
No Enc.: 1d6 (1d6)
Lair Probability: 20%
Movement: 120' (40'), Fly: 180' (60')
Armor Class: 2
Hit Dice: 7 to 9
Attacks: 1 (see below)
Damage: 1d10, drain life energy (see below)
Save: F7 to F9
Hoard Class: XVII
The vampire is a hateful undead creature created by means of an abhorrent necromantic ritual that requires the free and active consent of a human (and only a human) being to effect. The vampire survives only by drinking the blood of the living. It is immune to sleep and charm spells and can only be struck by magical weapons. If damaged, a vampire regenerates 3 hit points per round. If reduced to zero or fewer hit points, it is not destroyed but rather reduced to a gaseous form (which it can also assume at will).
A vampire is immensely strong, dealing 1d10 points of damage with each strike of its claw-like hands. Though this creature looks like a hideous, emaciated corpse, it nevertheless can exert a powerful attraction over mortal beings with its gaze, which acts as a charm person spell (save at -2 to resist). A vampire will drink the blood from a charmed victim, draining two levels with each feeding. Drinking blood cannot be done in combat and the victim will have no recollection of the event afterward. Victims entirely drained of all their levels simply die, but they may not be restored to life by any means, including resurrection. A vampire must drain a number of levels per week equal to its hit dice or it will permanently weaken, losing one hit die per week of insufficient sustenance.
Though powerful, a vampire will quickly disintegrate if exposed to sunlight. It cannot cross running water (which they cannot cross except by means of a bridge, boat, or similar construction) and impalement with a wooden stake immobilizes (but does not kill) it. A vampire is repelled by the scent of garlic or its reflection and can be turned by a cleric of sufficient level. During the day, this creature must return to a grave, tomb, or casket that contains soil from its native land or else it will lose hit die per night until it reaches 0 hit dice and fades away. Lost hit dice are restored at a rate of 1 per night of slumber in its proper hideaway.
A vampire can summon 1d10x10 rats or 3d6 wolves once per day, which arrive in 2d6 rounds to aid it. The presence of an active vampire creates a miasma that slowly spreads at a rate of 1 square mile per day up to a maximum number of square miles equal to the hit dice of the most powerful vampire in the area. Anyone within the miasma suffers a -2 to saving throws against diseases, curses, and similar effects.