Mental stress mechanics work very similar to physical damage mechanics. Use the Characteristics Table from p. 28 of the Player’s Guide. Instead of basing stats on TOU, base them on WIL. Instead of Wound Threshold, note the Trauma Threshold. Instead of an Unconsciousness Rating, not a Catatonia Rating. Instead of a Death Rating, note Insanity Rating.
Trauma are “mental wounds.” If mental stress from a single source meets or exceeds this threshold, a trauma is inflicted. Each trauma inflicts a temporary derangement, drawn from the pages of the Eclipse Phase sourcebook (pp. 210-211).
If this much stress is acquired, the character enters a catatonic fugue state until the stress is reduced.
A character reaching this point goes batshit crazy insane. The player may continue to roleplay this, or the GM may transform then into an NPC depending on the situation. Unless the character receives immediate treatment, they will be mentally lost for good.
If 3 or more trauma are acquired at once, or if the character reaches their Insanity rating but is treated, the character acquires a semi-permanent disorder. These are based on the disorders in the Eclipse Phase book, starting on . 211.
Characters receives stress recovery tests just like physical damage recovery. The amount and step is based on WIL. Traumas may only be healed when all stress is eliminated by spending a recover test. Only one trauma may be healed per day. Disorders may only be treated with extensive long-term care and magic.
Anti-Stress Talents, Spells, and other Magic
Still working on this—I’m open to suggestions here. I will likely introduce a soothing tonic or calming herbal remedy that acts as a booster potion for stress recovery. Some talents and spells may provide a type of “mental armor” against stress. I will likely allow talent knacks for Heartening Laugh, Inspire Others, Lion Heart, Temper Other, and Temper Self that do this. A knack for Steel Thought will allow it to be used as an “avoid blow” against mental stress. Knacks for Blood Share and Fireblood could be used to heal mental stress.
I haven’t had a chance to look at spells yet. If you think of anything good, throw it at me.