1 Lifesteal per 120 Conversion Points
The vampire is a monster class, and has its own custom conversion bonus. This bonus is 1 lifesteal for 120 conversion points. The vampire's long list of disadvantages and his utter reliance on his lifesteal class feature makes him one of the most difficult classes to play, second only to the File:Human Goatperson.png Goatperson in learning curve. He's incredibly vulnerable to bloodless monsters, so it's important to keep track of which monsters have this trait, and which do not.
The vampire's healing rate does not improve as he levels up, and he cannot regenerate mana unless he's at full health. While he can explore to recover at the 1st and 2nd level, it quickly becomes impractical to do so beyond this point. You will eventually need to rely primarily on your lifesteal, allowing you to conserve exploration tiles for recovering mana. However, monsters and their bloodpools are non-renewable resources, so tapping your reserves too soon can be highly detrimental.
One useful approach to playing vampire is to cultivate "blood cows". To do this, identify high-health/low-damage enemies ( Meat Man works best) and avoid killing them. Once you are a higher level than they are, your lifesteal will vastly exceed their damage output. Because these monsters have high hit points, your attacks won't actually kill them. When you next explore, your blood cows will heal and you can repeat the process later. With enough blood cows, a vampire can effectively eliminate his regeneration issues.
The vampire benefits from first strike and dodge more than than other classes due to his focus on lifesteal, making the GETINDARE glyph incredibly valuable to him. Remember that if you strike second, the enemy's damage is applied before your lifesteal and can potentially kill you. Where most classes can get one extra hit from first strike, a Vampire can get several extra hits. His hampered health regeneration means that LEMMISI and APHEELSIK are useless and can be converted on sight.
The Platemail item is particularly useful to the Vampire if he cannot find the first strike glyph. Although he will always strike second, the damage reduction has a wonderful synergy with his lifesteal. A 10th level vampire with platemail and many layers of lifesteal can effectively cancel out the first 70-90 points of damage, enough to make winning any non-vicious scenario trivial. The Vampire's immunity to poison and mana burn afflictions (similar to the Crusader) gives him a special affinity with Patches. Because he's immune to two of the "bad things" Patches can invoke, this cursed teddy bear is all carrot and no stick for a vampire.
It is important to note that your lifesteal is capped by your damage output. With a sufficient number of CP (and especially with a Vampiric Blade prepared) this can become a serious bottleneck. Preparing extra attack boosters or the Perseverance Badge can be very useful to avert this limitation. You also cannot steal more life than the enemy has; this is especially notable with enemies that have Death Protection, since they will be reduced to 1 hit point between attacks. In cases like these, you should explore to allow your enemy to heal (but not too much!) so you can steal more life when you next hit them.
Vampires could originally worship deities, but the problem was that they were absurdly overpowered with Dracul. Rather than nerfing them into the ground, the devs just changed them so they couldn't worship deities. It was the most graceful solution available to a glaring balance problem. There was a brief period where they could grab Pactmaker Pacts, though :-P