As heroes traverse the darkness of the dungeons, they accumulate stress. If left untreated, high amounts of stress can mean the demise of the hero, and their companions.
Stress is mainly gained by fighting during expeditions, through monsters' critical strikes and some particular attacks that specialise on dealing stress damage. A small amount of stress is also gained when entering a dungeon (depending on its level and the hero's resolve) and while travelling through it, and its magnitude is greatly influenced by the amount of light that the adventurers have at their disposal during any stressful event. Extra stress damage is suffered if walking backwards through a corridor, when getting hit by traps, or through some interactions with curios, as well as when prolonging a fight excessively. Heavy stress damage will also be applied, together with health damage, when failing to satiate a hungry party, when removing obstacles without the use of a shovel, or when witnessing a comrade either reach Death's Door or die. Many negative quirks will increase the amount of stress suffered by a hero in certain situations, as will the drawbacks of many trinkets.
Unlike combat damage, stress is not fully healed when finishing a mission. When returning to the Hamlet, stress levels are capped to 100. Stress persists on the heroes, rendering treatment mandatory in order to make use of a stressed hero again without heavy drawbacks, and causing difficult decisions such as retreating from a failing expedition more grave, as fleeing from fights and missions also stresses out the heroes.
The stress bar is a gauge from 0 to 200, with a threshold at 100 stress points: once this level of stress is reached, the hero will gain an affliction, with a chance of becoming virtuous instead. A hero that's neither Afflicted nor Virtuous cannot have more than 100 stress; if something would cause their stress to exceed 100, their resolve is immediately tested. Afflicted heroes will often disobey the player's commands and will hinder the mission by inflicting additional stress damage on themselves and the party, potentially dragging their comrades along in their path to madness. Upon reaching 200 stress, a character will suffer from a heart attack and will either enter Death's Door or, if already on Death's Door, die outright. However, heroes that become virtuous will instead, upon reaching 200 stress, have their virtue removed and stress reset back to 0.
Despite the many possible sources of stress, there are also various ways of preventing and healing the stress accumulated during quests: the most typical and effective way is using two of the facilities available in the Hamlet, namely the Tavern and the Abbey, which, for a cost in gold and by holding the hero for a week, will relieve them of a large amount of stress, also ridding them of any acquired affliction. A hero that is left idle in the estate will recover 5 units of stress each week, increased to 15 a week with the fairly inexpensive Puppet Theatre District.
It is also possible to relieve stress during an expedition, by using some camping skills at the disposal of many heroes, or during fights by using certain abilities. Stress will also be healed when dealing critical strikes, killing enemies, receiving critical heals, disarming traps, or interacting with certain curios.
The player can utilise a strategy where a hero can 'stunlock' enemies and use this extra time to have heroes with stress-healing abilities restore the party's stress. However, by doing so, the player runs the risk of encountering enemy reinforcements, as more enemies will appear if the party lingers with a single enemy for too long.
- Many quirks and trinkets can reduce the stress suffered by a hero, both generally and under certain circumstances.
- Many camping skills can buff heroes by reducing the amount of stress suffered for several battles, or heal certain amounts of stress directly. In particular, Encourage and Pep Talk are camping skills which heals stress and buffs stress reduction, respectively, and may be learned by all Heroes, except for the Flagellant.
- Many Curios can heal stress, usually when interacted with using a particular supply item with the right object, such as the Confession Booth and Holy Water.
- Traveling at higher light levels provides a blanket percentage reduction on Stress inflicted.
- Scouting indirectly prevents stress by allowing detection of traps, granting a chance to avoid or disarm them. Successfully disarming a trap heals stress as well (8).
- Quickly eliminating stress-focused enemies such as the Swine Wretch or Cultist Acolyte can greatly reduce the amount of stress you incur in the long run.
- Killing any enemy has 50% chance to heal a small amount of stress to the killing hero (3). A hero performing a critical hit on an active enemy will heal a small amount of stress as well (3). These effects may stack. Critical hits also grant other party members a 25% chance each of receiving a small stress heal as well (3). Critical heals also provide a slight stress relief (3) to a healed hero.
- Some Heroes' combat skills can heal stress for themselves (the Abomination's "Absolution" or Leper's "Solemnity"), or others (Crusader's "Inspiring Cry" or Jester's "Inspiring Tune"). In addition, Crusader, Jester and Houndmaster have access to trinkets which increase the amount of stress healed with their skills.
- Any hero who becomes Virtuous goes from 100 Stress down to 45, and grants a small stress heal (6) to all other members of the party. Certain Virtuous states will also grant the Virtuous hero a continuous stress resistance buff or actively heal the stress of either the Virtuous hero (15) or others (3).
- Inversely, heroes who becomes Afflicted will inflict stress on other party members, and will continue to do so as long as they are afflicted. Avoiding Affliction is paramount to avoiding large amounts of stress in the long run.
- Using heroes infected with the Crimson Curse who are Craving and Wasting interact with Curios can prevent stress damage, as these heroes can deal stress damage when other heroes interact with Curios.
- In all states of Crimson Curse (except Passive), heroes can inflict stress on allies in the same vein as Afflicted ones, although heroes in Bloodlust state also have a chance to heal their own stress (15) at the start of the their turn.
- Sources that reduce the amount of stress damage received cannot exceed reducing this by 80%.
In this PvP game mode, several of the heroes' skills have been reworked to always induce Stress or inflict Horror, allowing for a Stress-focused party to function. Stress-based parties focus on a battle of attrition, aiming to get every enemy Afflicted before pushing them into suffering from Heart attacks repeatedly until they succumb. Some variations combine stress with Bleeds and Blights, and use those ailments to push the opposition to Death's Door repeatedly for extra Stress and greater chances at inducing heart attacks.