Your vampires (gained at Feudalism, or through Losha Valas at Fanaticism) can be fed either through building a couple of big farm cities, or simply by taking over enemy cities and gobbling up their entire population (bon appetit). Spread the gift to as many of your units as you can (your Moroi units can gain vampirism earlier than other units) and take over the world. With their unique Breeding Pit building, the Calabim also have synergies with the use of slave labor - whenever your citizens aren't being used for vampire food, they can be whipped away for production. (Your citizens may feel a bit unhappy, but they'll be dead soon enough anyway.) The Calabim World Spell, River of Blood, grants 2 population in each of your cities, while reducing the population of all other cities in the worl