#that but no; it's in the sourcebook that says “vampire pcs are badwrongfun and you can never have them”

[y-rhywbeth2]

Guess who found more vampire lore that would've been helpful earlier! (This is what happens when you skim the mechanics pages too fast...) Turns out there are concrete rules about how much blood vampires need.

Vampires require 12 hit points worth of blood every 24 hours (the amount of blood you'll get from draining 2-3 people or 12 rats dry, mechanically. The designers maybe didn't think this through...) The source is immaterial, and may come from people, corpses or animals. They're all just as good, though fluff wise they won't feel good subsisting on animal and dead blood (there are no mechanical penalties). The blood doesn't have to be fresh or taken directly from the vein, you can keep it stored in a fridge or whatever equivalent.

Vampires lose the power boosts they gain with age if they don't get enough blood, but cannot regress below the level of a newborn vampire. Age categories aren't present in later editions, so basically: vampires and spawn can't get any weaker than the base stat block given for them in the monster manual. They do lose a hit dice per day without sufficient blood (blood is required to maintain the physical body, their bodies will slowly revert into corpses without it.) They will, however, eventually lose control of themselves if they wear down to a single HD and revert to a state of mindless animal hunger and go on a bloodthirsty rampage draining the blood out of any source they can get their hands on. (Failure to get any blood at this stage causes the hibernation state as they become trapped in their own withered corpse unable to move until somebody feeds them blood.)

HD recover rapidly with sufficient nutrition; regaining 1 per every day of full feeding.