“This is not blood magic. This is blood science!”
–Dr. Peter Blood, physician/pirate
The Red Doctors are a college of physicians who heal their patients through a course of bleeding (the blood does not always come from the patients). In towns where the temple healers might not take you, the Red Doctors will.
The Red Doctors offer the following services:
Phlebotomy (Cure wounds cast as level 1): 100 gp and the patient’s max HP is reduced by 1. Like all maximum hit point damage, this damage goes away with a long rest.
Operation (Lesser Restoration): 300 gp and 3d6 damage to patient’s max HP.
Transfusion (Raise Dead): 500 gp and an extra corpse, unwounded, extremely fresh (no questions asked about either corpse provenance. No guarantees, no returns, no exorcisms in the event of accident)
So much for the Red Doctors as a replacement for NPC healers. But in a dark setting, with a PC Red Doctor, you could roll on happily without either clerical healing or Hit Dice healing.
The Red Doctor abilities hit the highlights of the clerical healing list: they don’t mimic every clerical spell, obviously, but arguably they’ve got everything that’s absolutely required on a day-to-day basis: healing, curing, and resurrection. The nice-to-have’s, like Turn Undead, are, in this case, don’t-have’s. That might be a feature in a Ravenloft game.
I like Phlebotomy as a straight-up replacement for Hit Dice. There’s no spell-slot cost to this Cure Light Wounds effect, so it can be done infinite times per day, but there is a cost: 1 max HP damage per 1d8 HP healed. Instead of ticking off daily HD and then hitting a wall, you’re watching your max HP diminish every time you heal, which is a nice way to model decreasing stamina in terms of resource management, instead of imposing, say, penalties to d20 rolls.
In a world without clerics or HD, I’d make the Red Doctor abilities widely available. I might make them a feat, or even consider giving them to anyone who is trained in medicine. Here they are as a feat.
Bachelor of Sanguinity
If a PC studies at the Red Doctor school (a study which requires downtime and a fairly steady supply of fresh corpses), he or she gains the following abilities. (In the sinister jargon of the red doctors, a patient is any humanoid creature, Small or larger, that bleeds when cut. An intact corpse is one that has no external injuries and hasn’t shed blood in the past day. I use these terms in the following description.)
A Bachelor of Sanguinity can use the power of a patient’s blood to cast magic spells, using Intelligence as spellcasting stat, without the use of spell slots.
Phlebotomy. As an action, the doctor may draw blood from a willing or helpless patient. The creature’s hp and maximum hp are reduced by 1. If the patient’s HP hits 0, it dies. Otherwise, as part of the same action, the red doctor may cast Cure Wounds as a first level spell on the patient. Higher levels: at each odd level after the first, the doctor can perform the Cure Wounds at one spell level higher, up to a maximum of 5 maximum HP reduction and 5d8 + Int bonus healing at level 9.
Available at 3rd level. Operation. The doctor may spend 10 minutes bleeding a helpless patient, reducing its hp and max hp by 3d6. If it falls to 0 hp, it dies. If it survives, the doctor may cast Lesser Restoration on the patient.
Available at 5th level. Lobotomy. After a 10-minute procedure, the doctor may turn one intact humanoid corpse into a zombie. The zombie is loyal to the doctor indefinitely. The doctor may only control one lobotomized zombie at a time.
Available at 9th level. Transfusion. In a 10-minute procedure, the doctor drains all the blood from an intact humanoid corpse. The doctor may then cast Raise Dead with no material component on a different corpse within reach. There is a slight chance of failure (see below:)
1: The resurrected body is possessed by the soul of the transfusion donor as if Magic Jar had been cast. This may not be immediately obvious.
20: The resurrected body is undead. If you’re feeling nice, consider giving it the Revenant template from Unearthed Arcana.
I designed the Red Doctor abilities so that the low-level ones are fairly benign, and they get creepier at higher level. Being able to raise a zombie, and being incentivized to “find” fresh corpses, make sense as capstone abilities in a world where knowledge corrupts.
In the right setting, though, this feat doesn’t have to represent only sinister, evil doctors. It can also represent the skills of a standard non-magical physician. After all, Renaissance doctors tried approximately this same stuff, except without the benefit of healing people, and with the additional tendency to poison people with mercury. And Renaissance folks (mostly) didn’t think doctors were evil.