Cross-posting this from my blog, because I'm sure you guys will have some wonderful insights.
TL;DR - I think Willpower affecting both Lucidity and Composure is a problem. I explain why and propose alternatives.
Willpower is kind of Constitution of the Mind, to borrow a D&D metaphor. Unlike the other aptitudes there's very few skills it affects (none in fact except for the Psi skills, which we'll look at in a later edition), instead it serves three purposes:
1 - It defines a character's Lucidity, their ability to absorb mental stress and how much shit they can take before they lose it
2 - It defines a character's Composure(WILx3), how likely a character is to take stress damage from existential crises and extraterrestrial horrors
3 - It defines a character's Trauma Threshold, how much mental stress they can absorb before developing derangements
Ability to resist trauma grows linearly with Willpower; a character with 5 WIL a 15% chance to resist trauma, a character with 10 WIL has a 30% chance, a character with 15 WIL has a 45% chance and so on up to 90% at 30 WIL. This is all well and good.
Lucidity is defined as twice a character's Willpower, and thus also scales linearly - as does Trauma Threshold at one-fifth LUC. Witnessing a gruesome murder scene clocks in at 1d10 stress, or 5.5 on average. A character with 5 WIL and 10 LUC can't do that more than twice on average without going batty, and even once is likely to earn a Trauma. A character with the full 30 WIL, however, has 60 LUC and a TT of 12.
This is intuitive: if Willpower represents an ego's ability to keep hold of reality, then it follows that someone with high Willpower would be better able to deal with disturbing situations. The problem is that Willpower double-dips: A character with low Willpower has a small chance to shrug off mental stress, and will statistically fail their WIL x3 test and take stress damage more often. That same character has a lower Lucidity, and thus is able to absorb less mental stress before going insane.
At the other end of the spectrum, a character with high Willpower has a better chance of passing their test and not taking any stress. If they do fail a test, they can absorb more stress than other characters before insanity takes hold.
In essence Willpower has an exponential effect on a character's ability to keep hold of their sanity, as it affects both one's chance of taking mental stress and how much mental stress they can take. This is particularly egregious in the context of asyncs; in the setting lore asyncs, in particular the Lost Generation, vary from mildly disturbed to spree-killing insane. However, since Psi skills and sleight durations are based on Willpower a character with the Psi trait is encouraged to emphasise their WIL in order to optimize their psi abilities - the result is that characters who should have the most tenuous grasp on sanity are, mechanically, significantly more mentally stable than non-asyncs.
I've thought about this for a while, and I can think of four ways to address this dissonance between fluff and mechanics.
1 - Divorce Lucidity from Willpower and base it on some other aptitude - This would result in high-WIL characters who could shrug off stress most of the time, but whose minds would start to fracture if they let their guard down.
2 - Remove Composure, at least as a test to avoid taking stress damage. Stress damage is already a die-based variable, and Lucidity a measure of how much a character can take. Rolling extra dice is unnecessary complication.
3 - Divorce Composure/Resolve from Willpower and base it on another aptitude or aptitude spread - High-WIL characters would be better able to absorb and internalize trauma, though not necessarily brush it aside. I would suggest COG+INT+WIL as the alternative to WILx3.
4 - Make Composure/Resolve a skill rather than an Aptitude test. This is sort of an alternative to option 2, but divorces Composure from aptitudes entirely. It becomes a defensive skill analogous to Fray. Of course this also means it's easier to raise and easier to minmax so I'm not sure it's strictly better than option 2.
I'm not sure if any of these are strictly "better", but I'm sure there are alternatives I'm overlooking. What are your thoughts? Is it even a problem that Lucidity and Composure are derived from the same aptitude?
Thermonuclear Banana Split - A not-really-weekly Eclipse Phase campaign journal.