At the best of times, the Underdark is a bizarre, alien, and inhospitable world, but the influence of the demon lords has transformed it into a domain of madness and chaos. Faerzress acts as a catalyst, spreading the demon lords' madness throughout the Underdark.
Once the party escapes Velkynvelve and strikes out into the Underdark, begin taking into account the effects of demonic madness on the characters' sanity (see "Madness" in chapter 8 of the Dungeon Master's Guide). At various times in the adventure, characters will be called upon to make a saving throw to resist some madness-inducing effect. In addition, you can have one or more characters make a saving throw against madness whenever one of the following events occurs:
- The characters encounter or witness something particularly alien or disturbing (such as a demon lord).
- The characters stay in a Faerzress-suffused area for a long time (8 or more consecutive hours).
- A character takes psychic damage, particularly in an area suffused with Faerzress.
In Out of the Abyss, madness is measured in three levels:
Madness Levels
| Level | Effect |
|---|---|
| 1 | Bout of short-term madness (lasts 1d10 minutes) |
| 2 | Bout of long-term madness (lasts 1d10 × 10 hours) |
| 3 | Bout of indefinite madness (lasts until cured) |
A creature's madness level starts at 0. When the creature fails a madness saving throw, its madness level increases by 1, and the creature immediately suffers the level's effect (as determined by rolling on the Short-Term Madness, Long-Term Madness, or Indefinite Madness table). When the effect ends, the creature's madness level doesn't change. Any time the creature's madness level increases, it suffers the effect of the new level.
If a creature with level 3 madness fails a madness saving throw, its madness level becomes 1. In this way, characters can potentially accumulate multiple forms of madness.
A Calm Emotions spell can suppress the effects of madness, while a Lesser Restoration spell can rid a character of a short-term or long-term madness. Given the demonic source of the madness, Remove Curse and Dispel Evil are also effective as cures. A Greater Restoration spell or more powerful magic is needed to cure indefinite madness and also resets a creature's madness level to 0.
Short Term Madness
| d100 | Effect (lasts 1d10 minutes) |
|---|---|
| 01-20 | The character retreats into his mind and becomes paralyzed. The effect ends if the character takes any damage. |
| 21-30 | The character becomes incapacitated and spends the duration screaming, laughing, or weeping. |
| 31-40 | The character becomes frightened and must use his action and movement each round to flee from the source of the fear. |
| 41-50 | The character begins babbling and is incapable of normal speech or spellcasting. |
| 51-60 | The character must use his action each round to attack the nearest creature. |
| 61-70 | The character experiences vivid hallucinations and has disadvantage on ability checks. |
| 71-75 | The character does whatever anyone tells him to do that isn’t obviously self-destructive. |
| 76-80 | The character experiences an overpowering urge to eat something strange such as dirt, slime, or offal. |
| 81-90 | The character is stunned. |
| 91-100 | The character falls unconscious. |
Long Term Madness
| d100 | Effect (lasts 1d10 x 10 hours) |
|---|---|
| 01-10 | The character feels compelled to repeat a specific activity over and over, such as washing hands, touching things, praying, or counting coins. |
| 11-20 | The character experiences vivid hallucinations and has disadvantage on ability checks. |
| 21-30 | The character suffers extreme paranoia. The character has disadvantage on Wisdom and Charisma checks. |
| 31-40 | The character regards something (usually the source of madness) with intense revulsion, as if affected by the antipathy effect of the Antipathy Sympathy spell. |
| 41-45 | The character experiences a powerful delusion. Choose a Potion. The character imagines that he or she is under its effects. |
| 46-55 | The character becomes attached to a “lucky charm,” such as a person or an object, and has disadvantage on attack rolls, ability checks, and saving throws while more than 6m from it. |
| 56-65 | The character is blinded (25%) or deafened (75%). |
| 66-75 | The character experiences uncontrollable tremors or tics, which impose disadvantage on attack rolls, ability checks, and saving throws that involve Strength or Dexterity. |
| 76-85 | The character suffers from partial amnesia. The character knows who he is and retains racial traits and class features, but doesn’t recognize other people or remember anything that happened before the madness took effect. |
| 86-90 | Whenever the character takes damage, he or she must succeed on a DC 15 Wisdom saving throws or be affected as though he or she failed a saving throw against the Confusion spell. The confusion effect lasts for 1 minute. |
| 91-95 | The character loses the ability to speak. |
| 96-100 | The character falls unconscious. No amount of jostling or damage can wake the character. |
Indefinite Madness
| d100 | Flaw (lasts until cured) |
|---|---|
| 01-15 | “Being drunk keeps me sane.” |
| 16-25 | "I keep whatever I find." |
| 26-30 | “I try to become more like someone else I know—adopting his style of dress, mannerisms, and name.” |
| 31-35 | “I must bend the truth, exaggerate, or outright lie to be interesting to other people.” |
| 36-45 | “Achieving my goal is the only thing of interest to me, and I’ll ignore everything else to pursue it.” |
| 46-50 | “I find it hard to care about anything that goes on around me.” |
| 51-55 | “I don’t like the way people judge me all the time.” |
| 56-70 | “I am the smartest, wisest, strongest, fastest, and most beautiful person I know.” |
| 71-80 | “I am convinced that powerful enemies are hunting me, and their agents are everywhere I go. I am sure they’re watching me all the time.” |
| 81-85 | “There’s only one person I can trust. And only I can see this special friend.” |
| 86-95 | “I can’t take anything seriously. The more serious the situation, the funnier I find it.” |
| 96-100 | “I’ve discovered that I really like killing people.” |