What exactly, in this world, is life? ...Generally it is a somewhat poorly defined artificial set of characteristics, and not at all a separate thing in itself - and by that definition it can be a bit hard to speak of "making life possible". The exact same things and processes which take place in and make up living beings can be observed in a vast number of other places, and on the other hand, there is no discernible line between "living" and "not living" to begin with. (When does a chemical process start being alive?)
 - It doesn't help that the more advanced organisms still function mostly like colonies of much smaller beings rather than singular entities. White blood cells especially are essentially tiny amoeba ... a type of which actually physically goes and crawls up to nerve endings to ask the brain what it is supposed to do every now and then. And generally, the rest of the cells (except the ones dedicated to deal with this kind of thing) could not care less whether or not something or other somewhere else in the body is dead ... as far as they are concerned, they'd gladly continue living on, except at some point either the environment gets too toxic or - as generally happens first - they simply cannot find anything to sustain themselves on in the vicinity (since the heart has stopped and nutrients are no longer carried around - basically, when the heart stops, the other cells die simply because they "starve to death", and for no other reason whatsoever). If you take a set of cells out and put them in a nutrient solution instead, they will keep living on like nothing happened, aside of receiving very significantly decreased amount of external orders. If by any chance those cells have telomerasis activated, for whatever reason (many types of cancer cells, for example), then those are practically immortal on top of it. (And not only hypothetically so - there is a strain still in laboratories from a woman who herself died several decades ago, at the ripe age of 86...)
"Severe organ failure" is furthermore a rater questionable thing, since the body in entirety can circumvent plenty of things quite decently - happens often enough that people suffer no serious discomfort from it. It would actually feel more natural in those terms if mages often felt no immediate effects (unless very severe - more than quarter of all blood in body - blood loss occurs or something like that ... people often enough do not notice if they have heart attacks were a third of their heart dies, even) and randomly died a few days later. If it is the brain that gets damaged, though, then the change often is immediate and can be very drastic. 
...I am not entirely sure where am I going with this anymore, so I leave it at that until I figure out what I actually wanted to say. 

In any case, the statement of making life possible has never really made sense to me - these things always automatically work otherwise since that is a part of their chemical/physical nature, but now that the components are within a body physics suddenly no longer apply to them and suddenly they have to be "activated"? 
- Souls being mandatory for life (rather than just magic/afterlife), a common fantasy trope as it is, tends to be one of those things that I inevitably end up placing in the box of things I actively avoid thinking of (I probably have to find a bigger box for those things ... soon), since I cannot create anything even remotely reminiscent of a working system with them. My own fantasy settings actually have it established that souls do not exist at all as far as "mortals" are concerned (and mages are more weird compound beings rather than just ordinary mortals ... I guess I *could* have made everyone like that, though)...
 - - Uh, and if I am by any case bothering you with my incessant picking apart of things, then honestly, just let me know. It's just you've been nice enough to at least try to explain how everything might fit together, so I've dared to bother you more than I otherwise do...

(Does magical exhaustion never damage the brain? I'd assume thinking / controlling body / memories are at least tightly bound to it in Reniam cases, too... Uh, and mind exists separately from body in other than the figurative sense?)

- Why would the body alter itself after the soul? The soul has been described to "cling" to the body - things sort of get "pulled into place"?

On a random thought - do you (as someone as a person who uses character with a long-sword) know what half-swording is (since I haven't seen you describing anything like it IC, and it seems to be a bit little known that such thing exists, even if it is very useful technique utilized by both modern and old practitioners of sword art)?

(By the way, I did post in the collab some time yesterday ... with nothing but the number to go by it can be hard to tell.)

...I go back to coding and trying to figure out what I wanted to say with most of it. My thoughts are a bit of a mess at the time being.