So I'd created a NPC magus with a minor magical focus in glass and crystal, and I'd been thinking in this spell:
Heart of Glass, MuCo(Te) 45, R: Voice, D: Conc., T: Part.: turns the target's heart into glass. (Base 25, +2 Voice, +1 Concentration, +1 Part).
What effect do you think the spell would have? My fist thought was that it would probably kill the target. But in that case the duration wouldn't probably need to be Conc. But if duration is lowered to Momentary, then maybe the spell would just cause a momentary stroke, not enough to kill the target.
So I'm thinking in something like creating a more extreme deprivation category due to the absence of blood flow and heartbeat, where deprivation checks need to be made once per round. And also something like a huge reduction in the target's Soak, because a medium impact to the chest could make his heart break into glass shards.
You would need to change Target to Part, since you are only changing part of the target rather than the entire thing. You already list the modifier to the level for it and the little blurp after "T: Ind." should be kept since it clarifies which part is affected.
The Base 25 +1 Mag for Part is roughly the same level as the PeCo Base 30 "Kill a Human". Since Perdo Form should always be more effective in its limited range then non-Perdo, requiring at least Concentration to kill the target (and making it less efficient than PeCo) is the minimum.
Regarding the comparison with a PeCo killing spell, the spell itself isn’t intended as a killing spell (you can cast it over a mundane to make it more cooperative to your demands, for example), but being what it is it is going to cause harm and after a while kill the target.
So the questions would be: how to model that harm?, and how long until it kills the target?
A damage roll could be a way to handle it (that’s what they do anyway), but a little voice in my head keeps screaming “fast deprivation, fast deprivation!”.
Deprivation works. Though I would try to avoid creating addition rules for a simple spell, you can just require a Deprivation check every round. That way it is a standard Deprivation check with a spell specific length of time. Do not change the difficulty. You do need to decide if the fatigue would be short or long term. I would learn towards short since it is closer to lack of air than food/water.
The ultra fast (once per round) deprivation can kill in a minute and even someone with a Stamina +5 will almost assuredly be dead in two.
There are ways to make it faster, such as automatically taking a fatigue every round in which the target performs a physical action. This would reduce them to only three or four rounds (18 to 24 seconds) before they are unconscious.
detail- a stroke is an effect in the brain, a heart attack or cardiac arrest is stopping the heart.
I know personally I have apparently (according to an EKG) had a minor heart attack that I was unaware of, and did not collapse, so it certainly does happen.
True. Though changing someones entire heart to glass would be a major heart attack, compared to a minor which only affects a small portion of the heart.
Even a major heart attack however is different from a stroke since there is still oxygen in the blood which would be able to continue supplying it to the brain until all of it in the local area was depleted.
Of course in ME the body works on humors so there is not a hard connection between stopping the flow of blood and cutting off oxygen to the brain. Oxygen was not discovered until 1774 and would not even be considered. They were more along the lines of the air became 'foul' and that breathing good air (rather than a single unknown part of it) was essential.
EDIT: I spent about six months with electra tachycardia (sp?) where my heart rate would shoot up to a high multiple of what it normally was. There was an 'echo' of the signal telling my heart to beat that would randomly show up and cause my pulse to suddenly double or quadruple from one moment to the next. My pulse would jump to so high that there was not time to effectively draw in oxygen and get rid of waste gasses. While not as drastic as a complete stop of blood flow, the effects on me were similar to a heart attack. While I had to stop physical activity when it happen, I did not ever collapse.
To my mind, this spell should just turn the heart into glass. A perfectly functioning glass heart. Since the circulation of blood is not a thing, this should render the person more vunerable to shocks and heartbreak rather than outright kill them. Just because the spell is high level should not make it scary.
Why do you believe it would not be possible to target the heart? The Magus, if he has even rough knowledge of human anatomy, would know where the heart it. The spell is Target: Part, so it the spell is actually cast at the person even if it only affects part of them.
While it is only the cosmetic effect, Clenching Grasp of the Crushed Heart destroys the targets heart. If a spell could not be cast on a targets heart, then even the cosmetic effect of that spell would not be possible.
Healing spells will heal internal damage that the Magus can not see with no issue.
At the beginning of the eleventh century, Avicenna in his Canon of Medicine integrated Aristotle's ideas within his largely Galenic physiology when he wrote: "[The heart is the] root of all faculties and gives the faculties of nutrition, life, apprehension, and movement to several other members." He believed that heart produced breath, the "vital power or innate heat" within the body; it was an intelligent organ that controlled and directed all others. He identified the pulse as "a movement in the heart and arteries which takes the form of alternate expansion and contraction, whereby the breath becomes subjected to the influence of the air inspired."
if the caster is touching the external wall of a room, he can cast a Target: Room Corpus spell on the people within at Touch Range, even though he is not touching any of those people, and indeed cannot see them.
Further compare Curse of the Desert (PeAq25, ArM5 p123) which removes virtually all the fluid from a target's body; there's no possible way to see all of a target's blood and other internal fluids! Twist of the Tongue (PeCo30, ArM5 p133) doesn't require the target to have his mouth open and be facing you. And so on, and so forth.
Although nowhere expressly stated, it seems clearly implied that, if you can perceive an Individual, you can target any Part of it, even if you can't perceive the particular Part.
Agreed. The spell should in my opinion result in a person who happens to have a heart of glass - this might induce a vulnerability to blunt trauma and loud noises, though it might also make the person immune to Clenching Grasp of the Crushed Heart.
In my mind, Muto spells should not cause immediate harm, so the most harmful interpretation would then be some kind of deprivation. Perhaps an insidious emotional deprivation resulting in the loss of fatigue once every day?