Eldritch Magic

Version 0.10 · not yet playtested

Jon Mayo. PUBLIC DOMAIN (CC0-1.0)

Eldritch Magic

Eldritch magic is knowledge no mind was built to hold. Its power is real, but the reading of the sign, the speaking of the word, the glimpse past the veil, spends something that does not come back by morning: sanity. Where the arcane sorcerer refills a pool each night (see Arcane Sorcery), the eldritch scholar burns down a mind that heals only slowly, and pays for the deepest workings with a lasting derangement. This is the personal, mostly-permanent end of the family (see Alternative Magic Systems for the framework).

This supplement swaps the core’s stress fuel for a sanity track and its falter for a derangement. Everything else, the 3d6 ladder, the four magnitudes, magical harm, durations, the dry-caster poke, stands unchanged. If a rule is not below, it works as the core book says.

1 The Sanity Track

An eldritch caster has a sanity track of 4 + Wits points, drawn on the sheet. Wits is the casting attribute; forbidden lore is understood, not felt. Spend sanity to cast.

Magnitude | Sanity | What it does
Cantrip | 0 | A small wrongness, at will. Never spends sanity.
Spell | 1 | One real effect now: a psychic bolt, a fear, a grasping horror, a glimpse.
Greater spell | 2 | An area of dread, a summoned horror, a fold in space.
Ritual | 0 | Slow communion, out of a fight. Costs time, not sanity (but see below).

On a partial (9–12) take the reduced effect free, or spend +1 sanity for the full result. The buy is always optional.

2 Recovery (Slow)

Sanity does not refill on a rest the way mana does. A full night’s rest restores only 2 sanity. The mind mends slowly, and only quiet time far from the mysteries, a stretch of proper downtime, restores it completely. Plan a delve knowing the well trickles, not floods; a scholar who spends freely on the first day fights the last on a frayed mind.

3 Derangement (The Overfill)

You can always cast, the knowledge is there whether your mind can bear it or not. When you must spend sanity you do not have, cast anyway: the spell resolves, your sanity is stuck at 0, and you take a derangement, a lasting madness rolled below or chosen by the GM.

d6 | Derangement
1 | Phobia. A specific thing (the dark, deep water, crowds, fire) unmans you: −2 on any roll in its presence until you can flee it.
2 | Paranoia. You trust no one. −2 to act on an ally’s plan or accept their help until the scene turns.
3 | Compulsion. A ritual you must perform (count, cleanse, recite) before you act, or freeze for a round.
4 | Hallucination. You see and hear what is not there. The GM may lie to you about a scene once per session.
5 | Obsession. A fixation (a symbol, a truth, a person) pulls your attention; −2 to disengage from pursuing it.
6 | Fugue. Under stress you may lock up: on a miss in a hard moment, lose your next action to a staring spell.

Derangements are permanent until treated, by long care, a quest, or a cure rarely found. They stack. A veteran of the eldritch arts is a broken thing held together by will, and that ruin is the story the source tells.

4 The Dry Ember: Whisper of Unreason

Every eldritch bundle grants Whisper of Unreason, the at-will poke for a spent mind. One action, a maddening murmur at one target for 2 magical harm (ignoring armor), or leaving it briefly Frightened, one or the other, rolled to hit. It never rivals a real weapon or the bolt. Reflavor it, a wrong syllable, a half-glimpsed shape, but hold the cap.

5 Recommendations for a Playbook

Casting attribute: Wits. Lean the L1 grant toward Wits.

Spellcasting Advanced Action named in voice (the Delving, the Reading, the Communion). Grant a starting bundle: one cantrip, the Gibbering Bolt, and one ritual, plus Whisper of Unreason as the poke.

The sanity track (4 + Wits) on the sheet, with the derangement rule.

Fragile in mind, not soft in body. Give ordinary HP and light armor; the eldritch caster’s weakness is the slow ruin of the mind, not glass bones.

Speed 2, baseline.

Niche and lack. The scholar does fear, control, summoning, and forbidden knowledge better than anyone, and lacks a clean conscience, reliable healing, and a mind that stays whole.

Setting flavors:

The Occultist. A scholar who found the wrong book. Signature: a ritual of communion. Fits a world of hidden libraries and things best left sealed.

The Touched. Someone who saw too much and came back changed, power innate and unwanted. Fits a cosmic-horror frontier.

The Cultist. Sworn to an entity that answers. Signature: a summoning. Pairs naturally with a patron, and can share table with Demonic Summoning.

6 Sample Spell List: The Black Grimoire

A ready-to-use eldritch catalog, sorted by magnitude. Copy chosen entries onto a spell-book sheet. Damage numbers are the L1 default; a playbook’s damage step scales them. All damage is magical harm.

6.1 Cantrips (free, at will)

Whisper of Unreason. The poke: 2 magical harm, or brief Frightened, to one target, ignoring armor.

Eyes in the Dark. See in absolute blackness for a short while; the dark looks back.

Sense the Veil. Feel the uncanny nearby, a haunting, a thin place, a lie of the flesh.

Crawling Script. Read any writing, in any tongue, for as long as you study it. The letters seem to move.

Maddening Murmur. A wordless dread in one ear; a listener is unsettled, never harmed.

6.2 Spells (1 sanity)

Gibbering Bolt. The workhorse: 4 magical harm to one target, ignoring armor, as their own thoughts turn on them. On 18+, also brief Frightened.

Grasp of the Deep. A tentacle of shadow seizes one foe: 3 harm and Entangled until it tears free.

Veil of Wrongness. Concentration. Eyes slide off you; you are hard to notice or track while you hold focus.

Nauseate. One foe is wracked and Staggered, sickened for the round.

Whispers Between. Speak briefly with something not present, a spirit, a distant mind, the thing in the walls. Answers come slantwise.

Glimpse the Thread. Read a heartbeat of the near future: after seeing a roll, you may force one nearby creature to reroll it (yours or a foe’s).

6.3 Greater Spells (2 sanity)

Summon the Crawling Dark. Concentration. Call a lesser horror to fight beside you for a scene while you hold focus.

Unmake. A wave of terror fills a zone: 3 magical harm and Frightened to all within.

Warp Space. A passage folds: step across a zone, or seal a way behind you as the distance stretches wrong.

Devouring Shadow. Concentration. A zone drowns in living dark; those inside are blinded and take 3 harm each round.

6.4 Rituals (time, no sanity)

Commune with That Which Sleeps. Ask an entity a few questions. It answers truthfully and takes its due: the GM may impose 1 sanity of cost per answer.

Open the Way. Anchored (a sign in salt and ash). Tear a gate to elsewhere. What comes through is not always what you called.

Ward Against the Outside. Anchored. A circle that the uncanny cannot cross until it is broken.

Scry Through the Veil. Watch a distant place or person through a dark mirror or still water.

Bind the Name. Learn the true name of a spirit or horror, gaining power to command or banish it.