Adapting the Stress rules from Blades in the Dark, Liminal Horror, or Mothership.
When confronting horror and incomprehensible experiences, characters make a Wisdom saving throw versus a DC that varies on threat. (DC 15 by default.) On a fail, the character earns 1 or more Stress points. When a character’s Stress exceeds the character’s Wisdom score, the character suffers a Panic Response.
Examples of Stress
* 1 Stress: Witnessing something horrid. Unexpectedly finding a dead body. Graphic violence in real life.
* 1d3 (1d6/2) Stress: Witnessing horrific scenes or weird alien vistas. Unexpectedly finding the dead body of a loved one. Brutal graphic violence in real life. Seeing a minor eldritch horror (Hit Dice 1 to 3) for the first time.
* 1d6 Stress: Witnessing the death of a loved one. Meeting someone you know is dead. Awakening trapped in a coffin. Seeing a major eldritch horror (Hit Dice 4 to 9) for the first time.
* 3d6 Stress: Undergoing torture. Seeing a monstrous eldritch horror (Hit Dice 10 or more) for the first time.
Panic Responses (1d20)
* 1 … Severely Traumatized. You suffer the same effects are Shattered plus suffer 3d6 psychic damage.
* 2 to 4 … Traumatized. You suffer the same effects are Shattered plus suffer 1d6 psychic damage.
* 5 to 9 … Shattered. For 1d6 rounds, you are Incapacitated, can’t take any action, Bonus Action, or Reaction, but your movement is not hindered. Your Concentration is broken. You can’t speak. If you’re Incapacitated when you roll Initiative, you have Disadvantage on the roll. If you suffer further Stress failures, roll on this table again.
* 10 to 14 … Frightened. For 2d6 rounds, your base survival instinct takes over. You have Disadvantage on ability checks and attack rolls while the source of Stress is within line of sight. You can’t willingly move closer to the source of fear. If you suffer further Stress failures, roll on this table again.
* 15 to 19 … Exhausting Adrenaline Surge. You gain the benefits of Adrendaline Surge noted below, but when the bonuses end, you gain +1 level of Exhaustion when the surge subsides. If you suffer further Stress failures, roll on this table again.
* 20 … Adrenaline Surge. Your “flight-or-flight” survival instinct takes over. You gain Advantage on attack rolls and +5 feet Speed for 1d6 rounds, after which these bonuses end. If you suffer further Stress failures, roll on this table again.
Relieving Stress
During a short rest, you may make a Wisdom saving throw against a DC equal to your current Stress points. If successful, you reduce your Stress by your Wisdom modifier (at least one Stress point). If you fail, you gain 1 Stress point.
At the end of a long rest, you automatically reduce Stress by your Wisdom modifier (at least 1 Stress point).
A character doubles the number of possible Stress points reduced during a rest by also engaging in some form of dissipation: Revelry, debauchery, consensual sex, drinking, or otherwise doing some form of self-indulgent escapism. (Keep in mind X-card use and the “fade to black” take-it-as-written safety tool rule in Lines and Veils.)
Other Uses
Corruption: Coming into the pressence of pure elemental evil (e.g. the Loc-Nar from Heavy Mental) or carrying an evil artifact (e.g. the One Ring from Lord of the Rings) may have detrimental effects on a character. Follow the Stress format above to track Corruption Points against a character’s Wisdom or Charisma score (whichever is higher). Create a Corruption Response table, something akin to the Dark Gifts in the Ravenloft campaign setting. Only taking short or long rests on sacred ground (a temple, a holy site) or performing acts of pennance (GM’s discretion) allow for Corruption Points to be removed.
Mutation: Exposure to cosmic radiation or magical energy can cause physical and mental changes in a creature. Follow the Stress format above to track Mutation Points against a character’s Constitution score. Create a Mutation Response table, something akin to the tables found in Gamma World. Normally there is no way to remove Mutation Points once acquired, as a body slowly builds up contamination and broken genetic code, but the GM may allow special devices to be found that can “reset” chromosomes and regenerate a body back to its natural form.