Strain refers to the mental weariness inflicted on a character by intellectual activities, intense concentration, social engagement, or neural technology. Many Study Abilities, as well as general rulesets such as searching, require a character to take a certain number of points of strain.

    Just as physical fatigue is represented by fatigue factor and degrees of encumbrance, mental strain is represented by strain factor and degrees of strain. Whenever you take strain, simply compare your old strain total to your new amount, and see how many multiples of your strain factor the number has met or surpassed. For every multiple, you gain one degree of strain. Likewise, whenever you reduce strain, you remove one degree of strain for every multiple passed below.

    All sentient characters have a strain factor. This number is normally equal to bINT plus 2. Many Attributes can affect strain factor. It cannot be less than 2. Non-sentient characters do not have a strain factor, do not take strain, and cannot perform any Ability or activity that requires taking strain.

    As your character gains strain, mistakes they make during mental tasks have a risk of becoming more severe. This is represented by an increased margin of failure for INT rolls; for example, a successful roll on INT would be unaffected, but one that fails by 4 would be resolved as though it failed by 7 if you have 1 degree of strain. As strain worsens, this effect spreads to DEX, and adds actual stat penalties in addition to the effect on margin of failure.

    The effects of strain depends on how many degrees you have:

    There is no 5th degree of strain; instead, any strain called for that would raise you to 5 times your strain factor or higher is converted to an equal amount of trauma. You cannot voluntarily perform activities that would create enough strain to convert to trauma. If you exceed the maximum due to a decrease in strain factor (rather than an increase in strain), only 50% of the excess is converted to trauma, with the rest discarded.

    If your character is one with many decisions to make about strain, it's important to think about how often and how much it's worth taking some. For example, an arcanist fuels a great many Abilities with strain, but only rarely do they make INT rolls, so it might be worth overloading themselves with strain at crucial moments. Meanwhile, a character who frequently uses Computer Hacking (Technology) might have to be more conscientious about preserving their mental state, due to the important INT rolls and dangerous margin-of-failure effects.

    In combat, degrees of strain are "updated" at the end of your turn, or at the end of the movement phase. That is, when you perform an action that causes enough strain to gain another degree, you may resolve that action and the rest of your turn before adding the effects of the degree. If you gain a degree during another character's turn, your degree's effects arrive at the end of their turn. Degrees gained during a movement phase have their effects arrive at the end of the phase. Outside of combat, degrees are updated after the activity that created them, or at the end of a persuasion round.

    Strain is primarily removed by 4-hour rests. Whenever you complete a 4-hour rest, you remove an amount of strain equal to your bINT. Strain can also be removed directly by Enlivening elixirs and some social actions, while Sedating elixirs, luxurious rest, and certain Attributes and Appeal Abilities can increase the amount removed by rest.

    Some rules can cause minimum strain. Your strain cannot be lower than your minimum strain; add together all sources of minimum strain if you have more than one. When the minimum is removed, it does not immediately take the matching strain with it; it must be removed normally (except when the same event, such as a rest, removes both minimum and current strain).

    Your minimum strain cannot be equal to or higher than 5 times your strain factor. You cannot voluntarily increase your minimum strain to such an amount. In the event that such an amount is still called for (either by involuntary sources of minimum strain or a decrease in strain factor), you must remove sources of minimum strain within 1 day; if you cannot lower the amount called for below 5 times your strain factor by then, your character suffers a debilitating mental break or insanity, and must retire from the current campaign.

    Some Studies grant various types of insight - points that can be spent to negate an equal amounts of points of strain. Different forms of insight are tracked and replenished separately, and are always restricted to specific strain costs, as detailed in that form of insight's rules; for example, if you have melee insight, you can spend it instead of taking strain for a Close Combat Ability. Depending on the character and the Study, insight might look like actual insights being remembered, or it might refer to muscle memory or other effects of training and practice.

    When using an Ability that is valid for a certain form of insight, you may pay for it by taking strain, spending insight, or a mix of both. Typically, it's better to spend insight than to take strain, if you have the option to do so; this is not only to avoid strain effects and save your strain capacity for other purposes, but also because insight is usually replenished more easily than strain is removed.