Gfrktyl

Alcohol. Alcohol is the solution to all your problems. Infection? Alcohol. Shock? Alcohol. Pain numbing? Alcohol. Blood loss? Guess what close blood vessels.

You give some to ingest internally and then use some rubbing alcohol. People like alcohol so much that they does your ritual for fun. Look up "scarification" on youtube.

You just have to know where to cut. Avoid the vital organs and blood vessels.

Lingchi (Chinese: 凌遲), translated variously as the slow process, the
lingering death, or slow slicing, and also known as death by a
thousand cuts, was a form of torture and execution used in China from
roughly 900 CE until it was banned in 1905. It was also used in
Vietnam. In this form of execution, a knife was used to methodically
remove portions of the body over an extended period of time,
eventually resulting in death.
https://en.wikipedia.org/wiki/Lingchi

I also remember reading a novel The travels of jaimie mcpheeters by Robert Lewis Taylor in which native Americans did a similar thing. I don't have access to the book now but it is available online in various forms including PDF.

Do the carving over a long period of time. The advantage here is you get scar tissue that forms the patterns. Divide it up into, say, a dozen sessions over the course of a year (or a month if you prefer, though that is harder on the body). With plenty of time to heal inbetween.

Blood loss is no longer a problem (unless it's gushing) because the victim will only lose some in each session. Shock is less of an issue. Pain is more manageable (you might want pain, but too much leads to shock, which can kill). Infection is more manageable.

You can do the sessions as prep work and then do some cutting in each body area to "connect" the runes or whatever is needed on the day of the sacrifice.

You specifically said that the gods grant dark magic to their priests. It doesn't seem too far-fetched that the priests are able to magically prevent the victim's death. If you wanted to be nice and scientific about it, you could say that the magic keeps the victim's blood from gushing from the cuts, that the holiness of the act prevents infection from corrupting the process, that the victim is spared death from unbearable pain by the divine blessing of the deity, etc. I don't know what the overall tone of your story is, but personally I think it's far more gruesome to say that pain, infection, etc, are mortal afflictions easily cast aside by the magic of the ritual, and that the victim is kept alive by the power of some divine will, forced to suffer through it as their body functions are taken into the hands of their god. Victims must go through the process, and the powers that demand such sacrifices grant their priests the magic to defy natural causes of death in order to ensure the completion of the ritual. "The victim writhed in agony as the knives did their work, but the arcane forces kept his heart beating 'til the end" is far more dramatic then "The victim was too sloshed to do more than moan weakly and piss himself."

Well you have to make deep sigils, but you haven't specified how wide the wounds are.

When the offering hasn't got wide wounds the offering won't die and the sacrifice can happen without any extra items. But you need to cut like a professional doctor and need a stoned or bound offering so the cuts don't miss or go too deep.

Since you have multiple gods, you have room to negotiate. Simplify the process to get better returns; or use a complicated process with greater rewards but much higher risk of the sacrifice dying to early and you get nothing. Most sensible gods will pick the first option, with only the nutty or ambitious ones insisting on the old system.

The priesthood can simply drop the gods that pick the old system and take up with the ones that are less demanding, especially since it will also cut down on the number of sacrifices needed (what, you think it's easy "convincing" the dumb mugs that it's in their best interests to die painfully?). The ones that don't, need to be watched out for.

It seems to me that the task of keeping the sacrifice alive is both made easier by the presence of the dark magic being used, and a test of the mastery of the one doing the sacrifice.

The sacrifice is already happening under circumstances favorable to the deity being petitioned, and there is a sacrificer's manual detailing what cuts to make, and how, and in what order. A deity whose instructions begin with the most fatal cuts is not likely to get many souls; but beyond that, once the first symbol and each subsequent symbol is complete, the divine energy begins to resonate within it, keeping the wound fresh and open, but also keeping it stopped. While there will be a little bit of bleeding while the symbol is being made, once it's complete it is wrapped in a shimmer of unearthly light or tangible darkness that keeps the blood from spilling out uncontrolled. Infection or blood loss aren't going to take the victim away before the end, so long as the ritual is done right.

But beyond that, the deities also value the quality of their agents on earth. A priest with a deeper understanding of and link to the symbols of his patron deity is much more able to affect the world in the deity's favor than an untrained acolyte (not to mention lending some of the intrinsic magic of his own soul to the task). So the sacrifice serves as a test of the priest's devotion and knowledge as much as a channel for the soul of the sacrifice to flow to the deity. After all, even a botched sacrifice is still much more likely to send the soul to the patron deity than a person dying on his own (if not as purely or strongly as a completed sacrifice); but a priest who kills his sacrifice too soon is likely to find that his own soul is required along with that of the soul upon the altar. For this reason, only those who are practiced in their deity's devotion and ritual should even attempt such a sacrifice, lest they be consumed as well. After all, what is it to the deity if he receives one properly sacrificed soul, or one botched sacrifice and the soul of his priest?

First is the victim willing? If so is there a reason they can’t be claimed pre-death as a build up ritual?

The willing participant knows the end is hell but their family get incentives from their demise as the sacrifice victim.

The person could be given pain killers and such and/or knocked out given some of the markings and save the ones that will come for death (like the head ones) for later. The person is then marked for their deity only and their scars tell the tribe ( if they are able to mingle in the world before death) who is the sacrifice (allowing them to gain incentives for their commitment) and who their family is so the tribe/city can honor them. The victim gains further incentive to move forward (or if they changed their mind it stops them from backing out) seeing their family (and former victim families) showered like this. If the person is still willing they can feel they are doing the right thing. If they wanted to change their mind they feel trapped as if the village is willing to shower gifts onto their family they're also willing to tear them apart if this person backs out.

Is there something against giving the sacrificee pain killers or is their suffering apart of the process? If it’s the later in order to give the god the best power possible I’d imagine this victim once accepted as such would begin a regiment to give them high pain tolerance so they don’t die of shock.

Alcohol could be another. Herbs is another, Or you could dull their pain with another pain like (make up something up) for instance a million super fire ants are placed into gloves which the victim is forced to wear they are bitten for an hour by these things. They put their venom into the victim and this intense pain lowers their attention to the scarring and some of the torture elements during the process. It also slows down blood loss and staves off shock.

By the time the victim becomes aware of what you’ve done to them they’ll be wishing for death and praying that you off them instead which could still be part of the process as well you’ve switched an unwilling to a hyper devotee of deity X and then the deity gets more power from it in return giving more X to their worshipers.

• Antibiotics against the infections


• Bloodpacks against the bloodloss and the shock


• Painkillers against the pain and the shock


• Sedatives


• Hypnosis

and:

• Training and Preparation. The human body is capable to endure a lot more if trained properly.