Vampirism

A player becomes a vampire after being bitten by one or after injecting vampire blood, which applies a timed effect called Sanguinare Vampiris that ends in the transformation. Vampires drink blood from animals or villagers instead of eating food, and a villager drained in one go dies, while a careful vampire can leave it alive or turn it into a vampire. Vampires gain levels through vampiric rituals and spend skill points on abilities such as night vision, bat transformation and teleportation. Sunlight damages them, so they usually hunt at night, sleep in coffins they craft and color, and rely on night vision.

Players who prefer the other side can train as vampire hunters, using crossbows and other weapons, collecting items and fighting stronger vampires to gain advanced skills, some of which turn vampire powers against them. Vampirism requires Guide-API VP on the loader it runs on, and the sun and night mechanics apply to whichever role a player picks. A server running it needs every connecting player to have it too. Files are published for Forge and NeoForge, across 18 release versions, 1.12.2 – 26.1.2, and the code is under the GNU Lesser General Public License v3.0 only, making the mod open source.