Spellcraft is a system for inventing, modifying, and discovering spells through dedicated research, built for D&D 5e.
\nSpellcraft is hard, slow, and dangerous by design. A successful project takes weeks of in-game time, real material costs, and there's a real chance of going wrong, sometimes badly.
\nJust like everything else D&D, DMs should feel free to adjust the system in whatever way best serves their story and players. The guidelines here are a framework to build from, not a strict rulebook.
\nSpellcraft is a free and open-source Wizzlethorpe Labs product. If you find it useful, please consider supporting us on Patreon. Check out wizzlethorpe.com for more free tools and content!
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The full Spellcraft system for inventing, modifying, and discovering spells through dedicated research. See @UUID[JournalEntry.78c48c34ea0c759f.JournalEntryPage.17caad79a944240a]{the overview} for what Spellcraft is and the design intent behind it.
\nWhen a caster wants to modify a spell or invent a new one, they make an Intelligence (Arcana) check, with these modifiers:
\nYou may choose to use the spellcaster's spellcasting ability modifier in place of Intelligence for the check. The approach described here intentionally favors wizards and artificers, who are already built around study and research.
\nBase spell required. Every spellcraft project takes a spell the caster currently knows as its base. The base spell defines the spell-level penalty and the proposed change defines the DC. A caster who does not know the base cannot research a derivative of it. They must acquire and learn it first through normal channels (teacher, scroll, captured spellbook). Spells that are themselves products of prior spellcraft count as known for the purposes of further iteration.
\nThe DM sets the DC based on how ambitious the proposed change is.
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n| DC | Difficulty | Craft |
|---|---|---|
| 5 | Trivial | Rename, reflavor, change visual manifestation (color, sound, sigil) |
| 10 | Easy | Change damage type or school |
| 15 | Moderate | Swap save vs. attack roll; reroll dice variance (e.g. 8d6 to 4d12) |
| 20 | Hard | New utility spell loosely modeled on an existing one |
| 25 | Very Hard | Trade single-target damage for AoE or multi-target |
| 30 | Almost Impossible | Genuinely new high-power magic (should probably be plot-gated). |
| Margin | Outcome |
|---|---|
| Beat DC by 5+ | Clean success. The spell works exactly as designed. |
| Beat DC by less than 5 | Success with a quirk. DM picks something minor and flavorful from the @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.eabae8aa4eb73888]{Quirk Table}. |
| Miss by 1-9 | Unstable. The spell works, but every casting triggers a roll on a chaos table (default: @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.dc9f3b2ab8ff762b]{Unstable Surge}; substitute any Wild Magic Surge table or the PHB / SRD version to taste). |
| Miss by 10+ | Research backfire. Roll immediately on the @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.87ea38838003d826]{Mishap Table}. The spell is not produced and the materials are consumed. |
How the new spell enters the caster's repertoire depends on the caster's class:
\nIf the inventor learned their magic through study, training, or prayer (Wizards, Artificers, Clerics, Druids, Paladins, Rangers), they can teach their invented spell to another caster of the same class. The student makes their own Arcana check at -10 to the original DC (rediscovery from a teacher or surviving notes is far easier than fresh invention). The inventor decides who learns it, and can hoard, charge for instruction, or share freely.
\nIf the inventor's magic is innate, inspired, or patron-granted (Sorcerers, Bards, Warlocks), there is no teaching mechanism. They can cast the spell, but they cannot transcribe or transmit it. Another caster wanting access would need to observe them cast and reverse-engineer a class-appropriate version through their own spellcraft project.
\nCross-class teaching (a cleric's prayer to a wizard's spellbook, etc.) generally isn't possible without the recipient running their own spellcraft project to derive a class-appropriate version.
\nA caster with an unstable spell can attempt to fix it with a fresh research cycle:
\nSome spells should not be invented via dice alone:
\nThese should require a story arc. Spellcraft can advance the arc but should not resolve it.
\nThe DC 15 (\"dice variance swap\") tier covers trades like 8d6 to 4d12. These have the same average damage, but different variance. Two expressions are variance-swap equivalent if their averages, rounded up, match. Use the calculator to compare across die sizes:
The width of each row's distribution is the visual proxy for variance. A narrow shape clustered around the mean (11d4) is more steady and predictable. A wide shape spanning the whole axis (3d20-4) is more volatile.
Roll tables for Spellcraft mechanics.
\n| Table | Dice | Entries | Description |
|---|---|---|---|
| @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.15db521001893e24]{Curses} | |||
| @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.87ea38838003d826]{Mishap Table} | |||
| @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.eabae8aa4eb73888]{Quirk Table} | |||
| @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.dc9f3b2ab8ff762b]{Unstable Surge} |
When a @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.87ea38838003d826]{Mishap Table} result inflicts a curse (a research attempt that misses by 10+ and then rolls 19-20), roll on this table or pick. Curses are permanent and last until removed by remove curse, greater restoration, or a major plot beat.
\nRoll — Permanent curses from a Spellcraft research backfire.
\n| Roll | Result |
|---|---|
| 1 | Mark of Failure. A glowing sigil appears on the caster's forehead, palm, or throat. It pulses faintly whenever they cast any spell, visible to anyone within 30 ft. |
| 2 | Bleeding Magic. When the caster takes damage, they lose one expended spell slot of the lowest level they still have remaining for the day (once per turn, as energy bleeds away from the wound). |
| 3 | Shadow Echo. Every spell the caster casts leaves a faint after-image of its visual effects lingering in the air for 1 minute, marking their casting clearly even to non-casters. |
| 4 | Whispering Tongue. Fragments of the failed spell's verbal components leak into the caster's speech at inopportune moments. Disadvantage on Charisma (Deception) and Charisma (Persuasion) checks. |
| 5 | Frayed Concentration. The caster has disadvantage on Constitution saving throws to maintain Concentration on spells. |
| 6 | Hollowed Spell. Pick one of the caster's currently-known spells. Before each casting of that spell, roll a d10. On a 1, the spell fails to fire and the slot is consumed. |
When a @UUID[JournalEntry.78c48c34ea0c759f.JournalEntryPage.cd7d42577a3d20d1]{Spellcraft} research attempt misses by 10+, roll on this table immediately. The components for the attempt are consumed regardless, and the spell is not produced. A result of 19-20 inflicts a permanent magical curse from the @UUID[JournalEntry.7ce576e09552e3cd.JournalEntryPage.15db521001893e24]{Curses} table.
\nRoll — Backfires when a Spellcraft research attempt misses by 10+.
\n| Roll | Result |
|---|---|
| 1–3 | The caster takes 4d10 force damage and is knocked unconscious. |
| 4–6 | A permanent visible scar appears at the spell's source point (hand, eye, throat). |
| 7–9 | The caster loses access to one currently-known spell of the target spell's level for 1d4 weeks. |
| 10–12 | A creature, object, or feature within 30 ft is permanently transformed in a small way (hair to snakes, table to stone, doorknob to mouth, etc.). |
| 13–15 | The failure clouds the caster's thinking. They have disadvantage on all Intelligence (Arcana) checks for 1d4 weeks and cannot start a new spellcraft attempt during that window. |
| 16–17 | The caster loses 1 Intelligence permanently. Restorable only via a 7th-level spell or a major plot beat. |
| 18 | A hostile magical creature manifests, drawn by the disruption. CR equals the target spell's level. |
| 19–20 | The caster acquires a permanent magical curse. Roll on the Curses table, or pick. Curses last until removed by remove curse, greater restoration, or a major plot beat. |
When a @UUID[JournalEntry.78c48c34ea0c759f.JournalEntryPage.cd7d42577a3d20d1]{Spellcraft} research attempt beats the DC by less than 5 (success with a quirk), the DM can pick or roll on this table. Quirks are cosmetic or flavorful, not mechanically punishing, and travel with the spell wherever it goes.
\nRoll — Cosmetic and flavorful quirks for a Spellcraft success-with-a-quirk.
\n| Roll | Result |
|---|---|
| 1 | The spell carries a distinct smell (ozone, lilacs, woodsmoke, brine, wet stone). DM picks at creation. |
| 2 | A faint chime, drumbeat, or tone sounds at the moment the spell resolves, audible within 60 ft. |
| 3 | The verbal component must be sung or chanted, not spoken. Casting in silence is impossible. |
| 4 | The caster's eyes briefly glow a specific color while casting and for 1 round after. |
| 5 | A small harmless creature (moth, frog, finch, mouse) manifests within 5 ft of the caster, lingers 1 round, then disperses. |
| 6 | The spell requires a pinch of an unusual but cheap component (graveyard dust, river silt, a pressed flower petal), consumed each casting. |
| 7 | Plants within 10 ft visibly bend toward (or away from) the caster during casting. |
| 8 | The spell's visual manifestation has an unintended secondary color (fireball laced with green sparks, healing light tinged violet). |
| 9 | Small loose objects within 5 ft (pebbles, leaves, dust, coins) lift an inch off the ground for the duration of the casting. |
| 10 | A specific minor sensation hits the caster on completion: a brief nosebleed, a single sneeze, a 1-minute ringing in the ears, hiccups. |
| 11 | The caster's hair, cloak, or clothing stands or stirs as if in a wind that no one else feels, for 1 round after casting. |
| 12 | The somatic component is unusually elaborate (a bowing flourish, a spinning step, a specific finger-knot). |
| 13 | A specific phrase, name, or invocation must be spoken as part of the verbal component (often the inventor's name, a mentor's name, or a phrase of nonsense). |
| 14 | Animals within 30 ft react audibly when the spell fires: dogs bark, horses startle, birds take wing, cats hiss. |
| 15 | The spell's effect briefly appears in any mirror or still water within 30 ft, even when the caster is not in line of sight. |
| 16 | The caster's shadow performs the somatic component a half-second behind them. |
| 17 | A small sigil appears in chalk-like dust on the nearest flat surface when the spell is cast, fading after 1 minute. |
| 18 | The caster's voice changes for 1 round after casting: deeper, higher, accented, or briefly someone else's voice. |
| 19 | The spell will not function in a specific innocuous condition (over running water, indoors, while the caster is sitting, in direct sunlight). |
| 20 | The DM picks two quirks from this table, or invents one of comparable scope. |
A curated table of standard mechanical effects for @UUID[JournalEntry.78c48c34ea0c759f.JournalEntryPage.17caad79a944240a]{Spellcraft}'s cast-time instability: when an Unstable spell is cast, the GM rolls here and the result fires alongside the spell's normal effect. The entries are all negative effects. If you'd rather use a more chaotic mix of fortune and misfortune, substitute any Wild Magic Surge table you like: the 5e PHB / SRD Sorcerer table, a community curation, or your own.
\nRoll — Standard mechanical chaos effects for cast-time instability.
\n| Roll | Result |
|---|---|
| 1 | Your hands burn. You take 1d6 fire damage per level of the triggering spell (minimum 1d6). |
| 2 | Static discharges from you. You and each creature within 5 feet of you take 1d6 lightning damage per level of the triggering spell (minimum 1d6). |
| 3 | A blast of force throws you back. You take 1d6 force damage per level of the triggering spell (minimum 1d6), are pushed 10 feet, and are knocked prone. |
| 4 | You teleport 10 feet in a random direction (roll 1d8 for the direction) to the nearest unoccupied space. |
| 5 | You are silenced for 1d4 rounds and cannot cast spells with verbal components. |
| 6 | You are blinded for 1d4 rounds. |
| 7 | You are frightened of the nearest creature for 1 minute. |
| 8 | Spectral chains erupt around you. You are restrained for 1 minute. You can use an action to make a DC 13 Strength check to break free. |
| 9 | You are knocked prone. |
| 10 | Your size increases by one category (as the Enlarge spell) for 1 minute. |
| 11 | Your size decreases by one category (as the Reduce spell) for 1 minute. |
| 12 | You polymorph into a random Small or smaller beast (DM's choice) for 1 minute. |
| 13 | Each creature within 10 feet of you (including you) gains vulnerability to one damage type for 1 minute. Roll 1d6: 1 - Acid, 2 - Cold, 3 - Fire, 4 - Force, 5 - Lightning, 6 - Poison. |
| 14 | Energy bursts outward. Each creature within 10 feet of you (including you) takes 1d6 damage per level of the triggering spell (minimum 1d6) of a random type. Roll 1d6: 1 - Acid, 2 - Cold, 3 - Fire, 4 - Force, 5 - Lightning, 6 - Poison. |
| 15 | A thunderclap rolls out from you. Each creature within 10 feet must make a DC 13 Constitution saving throw, taking 1d6 thunder damage per level of the triggering spell (minimum 1d6) and being deafened for 1 round on a failure, or half damage on a success. |
| 16 | The spell is redirected to a random valid target within its range. |
| 17 | The surge devours your reserves. You lose your lowest-level unexpended spell slot. |
| 18 | You shed bright light in a 30-foot radius for 1 minute. Attack rolls against you have advantage while you are lit. |
| 19 | You wink out of existence, banished to a harmless demiplane. You reappear in your space (or the nearest unoccupied space) at the end of your next turn, missing that turn. |
| 20 | The surge cascades. Roll twice more on this table and apply both results, ignoring any further rolls of 20. |