Spoilers

Vampirism

In the full game, using a Vampiric Fang turns you into a vampire. Blood becomes the need to watch. It drains as turns pass and drains faster in sunlight. The sun also burns you, so travel under cover or at night.

Feeding on a sleeping person takes three turns. They can wake during it, and repeated feeding can kill them. From the third feeding on that person, each completed feed has a ten percent chance to be fatal.

Bat form lets you fly through trees and bushes, but narrows your view. You cannot walk into a creature to attack or interact while in that form. You need at least 20 blood to enter it, and you return to your normal shape at ten blood or less. Nearby enemies can prevent you from changing into a bat.

Charm costs 15 blood and lasts up to 30 turns. You can't use it in bat form, while feeding, on a sleeping person or while you already have someone charmed. Charming a guard also needs Gorged satiation and at least 30 potency.

A moonwell offers a Cleansing Ritual when you carry Moonwell Water, Blessed Garlic and Purified Blood. It uses one of each to cure your vampirism.