why would multiple leeches be required to consume a victim?

[Erebus]

People in this world don't age naturally like in our world. All human beings are born with mana, which is a component necessary for magical ability. It also doubly operates as a symbiotic spiritual parasite that slowly drains you of life while bolstering your magical ability. As a person gets older, their youth/vitality/health gets leeched away by their spirit-self, bolstering their mana. However, due to the age of the individual, it becomes harder to access their mana in order to use it in spells. When a person dies, their soul, containing all of the mana they have gathered over the course of their lifetime, ascends to the spiritual plane and absorbed by God, fueling it with energy and bolstering its power.We are essentially bottomless receptacles for gathering energy, fattened up on mana to be harvested by our deity.

A leech is a derogatory name for an evil sorcerer who steals the mana of others to bolster their own supply, making their magic stronger. This is done through a magic ritual in which the person's mana is sucked out and consumed by the sorcerer. unfortunately, these rituals are dangerous to do alone. Trying to absorb a person's energy solo could lead to the sorcerer fulling themselves up with more than they can contain, exploding them from the inside. Therefore, multiple sorcerers are required to cooperate with each other, each gaining a portion of the energy and lessening the risk.

If we humans are unlimited jars for collecting mana, why would the ritual for stealing it require multiple people to perform?

 

[Futhark]

Getting too much at once?

 

[skip.knox]

I don't understand the question. You say that "... multiple sorcerers are required ... [to lessen] the risk." Then you ask why multiple people are required.

 

[Night Gardener]

Perhaps... mana acquistion could draw parallels from blood donors. The God can receive any mana type. But, from person to person, perhaps there are severe 'compatibilty' issues that can be a problem.
Or, if you don't want to think about blood-typing, think about this: what's the difference between donating blood in a clinic vs. a massive bodily trauma like an amputation or gunshot wound? Ultimately in both scenarios, blood is leaving the body. Why is one donor experience more desireable than the other?

If the God is the equivalent of the calm, sterile, controlled clinical environment that allows mana "donation" to transfer from the individual (yes I realize the person is technically dead by your setting) ...then these leeches are the cut-throat thieves intent to bleed a victim out anyway they can. There's a lot that could go wrong, and the leeches are NOT as sophisticated as the 'clinical setting' God. The God uses IVs and needles, these theives are using the equivalent of rusty hacksaws, broken glass and gasoline hose siphons.

If the safe process is 'biological death' followed by 'transfer to God', then perhaps the answer to why it is so dangerous is the whole 'donor is not actually dead' part? Trying to siphon mana from a living person would probably be very energetically messy and wildly unpredictable. You took a quick slash at this victim: did you cut their skin and muscles ...or did you just hit an artery?

Going back to the blood-typing analogy: If the mana you acquire in your lifetime it ultimately unique to you, and someone comes along and tries to siphon it off (without consent, if that plays a factor) then like biology, mana could be resistant to 'transfer' out of you while you're still alive. Not unlike trying to send out blood cells to clot a wound to stop hemorrhaging. Your body is rather found of retaining as much blood as possible. Mana could get attached to the individual in much the same way and have self-preservation mechanisms that can be impossible to accurately anticipate.

If you're the leech, the pay-off could be worthwhile but perhaps having another leech siphoning at the same time can mitigate some of the more dangerous complications that can arise from this innate mana reaction of 'Wait, the person-host isn't dead, and this individual trying to siphon me out is not God, so this is probably REALLY bad'.

Another idea for needing two theives, is to aide in the stolen mana getting acclimated to new hosts? This might be a crude comparison, but if the donor/victim is oil, and the thief is water, maybe the 2nd thief is there to act as an ...emulsifier? Especially if, like organ transplants, the theif's body (or mana) might reject the donated/stolen mana... or the stolen mana might actually reject the thief.

I'm not sure if these medical-biological analogies are the general direction you want to go with, but the simplest answer to your question might be an old one: there's safety in numbers. If someone has mana worth stealing, they also probably have mana that can really hurt you. Two thieves have a better chance than one at *not* getting their asses kicked by a would-be victim.