The core game fuels every spell the same way: casting spends stress, and spending past your last box makes you falter. That is deliberate. One fuel, one failure, learned once, and it works for wizard and priest alike. It is also setting-neutral on purpose, so the core never has to take a position on what magic costs a person.

A setting often wants magic to cost something with teeth of its own. Eldritch lore should fray the mind. Alchemy should warp the flesh. A demon’s gift should stain the soul. Blood magic should be paid in blood. This supplement is the framework for giving a tradition its own price without touching the engine everyone already knows, plus a family of companion supplements, one per source, each carrying a ready-to-use sample spell list.

None of this belongs in the core. A caster is still just a playbook that grants the Spellcasting Advanced Action and a bundle of spells; an alternative source only changes what the Spellcasting action spends and what happens when the well runs dry. If a rule below is not mentioned, it works exactly as the core book and the SRD’s authoring notes say.

1 What Never Changes (The Engine)

These are fixed. A tradition that breaks one of them is a new game, not a supplement. Build on them; do not restate them in a playbook.

• Casting is a Skill action on the 3d6 ladder. Roll your casting attribute, read 8− / 9–12 / 13–17 / 18+. Against a willing target, or with no one to stop you, skip the roll and just pay.
• The four magnitudes. Every spell is a Cantrip (free, at will), a Spell (one real effect), a Greater spell (area, control, or a big effect), or a Ritual (slow, safe, no fuel). Decide the magnitude first, then price it. Only the middle two ever spend the source.
• Cantrips stay free and toothless; rituals stay slow. No new fuel turns a cantrip into a free bolt or a ritual into a combat spell.
• Magic is magical harm. It bites creatures whose Bane is fire or blessing.
• The dry-caster minor attack. Every bundle grants one at-will minor poke, the ember left when the fire is out, capped below a real weapon and below the bolt.
• Durations: Immediate, Concentration, or Anchored (consume a component).
• The partial (9–12). The reduced effect is always free; the full effect is an optional buy. That buy is paid in the tradition’s own currency, whatever it is, one unit’s worth.

2 What You Swap (The Three Questions)

A magic economy is three answers. Write them down and you have a tradition.

1. The fuel. What does a Spell spend, and a Greater spell? Stress spends 1 and
   2. A pool spends points; a corruption track gains marks; blood spends Hit Points. Keep the 1-vs-2 ratio: a Greater spell always costs about twice a Spell.
2. The overfill. What happens when you spend past your limit? Stress falters (reset, take Shaken). Every source needs its own version: the pool that runs dry, the mind that cracks, the flesh that finally changes, the debt that comes due. It must hurt without being a one-cast kill.
3. The recovery. How does the well refill? Stress and a mana pool clear on a rest. Sanity, corruption, soul-taint, and burned Hit Points recover slowly or not at all. This one answer decides whether the magic is a tactical resource spent every fight or a strategic one spent across a whole career.

3 Two Axes

Place a tradition on two axes and its feel falls out of the geometry.

Renewable ↔︎ permanent. Does the meter reset between fights, or does it ratchet across the campaign? Renewable fuels (stress, mana) make the caster a burst engine: strong now, empty soon, full again by morning. Permanent fuels (sanity, corruption, soul-taint, blood) make magic a slow-burning meter that shapes the character’s arc. The renewable end is a tactical dial; the permanent end is a tragedy in installments. This is the single biggest lever.

Personal ↔︎ external. Is the price paid from the caster’s own body or mind, or owed to something outside them? A personal cost (blood, sanity, flesh) writes a tragic arc the player carries alone. An external cost (a demon’s ledger, a patron’s patience) puts a character across the table who collects, and gives the GM a voice to play. External costs run best as clocks; personal costs run best as tracks on the sheet.

Mana is the renewable, low-consequence baseline the other four deviate away from; it is the closest cousin of stress, so it makes the natural first read.

4 Balancing a New Economy

The core’s balance does not come from the caster’s HP or the size of the meter. It comes from the caster being burst, not endurance, and from a narrow kit (soft in a fight, light or no armor, one thing they do better than anyone). Armor access and the Advanced Action kit carry tank-versus-striker, not the fuel. So when you build a new fuel, protect the burst shape:

• The well must run dry in a hard fight. If a caster can throw spells all encounter without ever reaching the dry-caster poke, the economy is broken. Size the meter to about 4–7 Spells, or 2–3 Greater spells, per full charge, the same burst a stress caster gets from a track of 4 + Presence.
• Keep the 1:2 price. A Spell costs one unit, a Greater spell two, in whatever the currency is. Do not invent per-spell costs; price by magnitude.
• The partial buy is one unit of the same currency, and always optional.
• Overfill hurts, once, thematically. It should never kill in a single cast, and it should be a story engine the table will remember: a derangement to roleplay, a mutation to hide, a debt to dread. Overfill that only subtracts a number is just mana; reach for the theme.
• Do not stack a second cheap resource onto a full stress caster. See below.

5 Does the Caster Still Have Stress?

Yes. Every character keeps the core stress track, because stress fuels far more than magic: it pushes any action, resists a blow, powers non-magical Advanced Actions. An alternative source fuels only spellcasting. The caster’s stress track is untouched and still theirs for everything else.

This means an alt-source caster is, on paper, holding two meters. Left alone that would out-resource a core stress caster, who pays for magic and defense out of one purse. Close the gap by narrowing the caster, not by hedging the meter: key the source to an attribute that pulls them away from being also-good-at-everything, give them light or no armor, hold their martial kit thin. The tradition’s harsh overfill does the rest, and a source whose cost bites hard enough can even leave the casting attribute free: blood magic keys to any attribute and pays for that breadth in Hit Points. A blood mage with a fat spell budget is still one bad round from the floor; a sanity caster’s power is borrowed against a mind that does not heal by morning.

6 Mixing Traditions at One Table

Different casters can run different economies side by side, the party wizard burning mana while the warlock’s debt clock ticks, because they share the magnitude ladder. The GM prices every spell the same way for everyone (Cantrip / Spell / Greater / Ritual); only the meter each caster spends from differs. A spell written for one source ports to another by changing one line: what it costs. Keep a single spell list on the table and let each caster pay in their own coin.

7 Writing the Caster Playbook

We ship no generic playbooks; a playbook is always a specific archetype in a specific setting. So each companion supplement gives you the parts and a sample spell list, and you assemble the archetype your setting wants. A caster playbook on an alternative source grants:

• The Spellcasting Advanced Action, keyed to the source (name it in voice: the arcane Weave, the eldritch Delving, the demonic Compact).
• The source meter, drawn on the sheet: a pool to spend down, a track to fill, or a clock to tick. State its starting size and how it recovers.
• The overfill rule, in one line, named to the tradition.
• A dry-caster minor attack, themed and capped.
• A starting bundle: one cantrip, one spell (usually the bolt), one ritual, in voice, drawn or adapted from the companion supplement’s sample list.
• The usual L1 grant budget otherwise (attributes, skills, HP, Speed, a second Advanced Action). Lean the attributes toward the casting attribute and away from toughness; hold armor access thin.

Everything else, the six basic actions, the ladder, HP and armor, conditions, comes from the core unchanged.

8 The Family

One companion supplement per source. Each is standalone, and each carries a sample spell list in that source’s voice, sorted by magnitude, ready to copy onto a spell-book sheet.

• Arcane Sorcery — magic drawn from a mana pool. The renewable baseline; overfill is mana burn. The recommended first read.
• Eldritch Magic — knowledge that costs sanity. A mind spent down toward madness; overfill is a lasting derangement.
• Alchemy — power wrung from matter, paid in corruption of the flesh. Overfill is a mutation you carry for good.
• Demonic Summoning — borrowed from a patron against your soul. A debt clock; when it fills, the patron collects.
• Blood Magic — fuel torn from your own vitality, burning maximum Hit Points. Push too hard and you bleed out.

9 Considerations Checklist

Before you finish a new source, answer these:

• What does a Spell cost, and a Greater spell (about twice)? What is the partial buy?
• What is the overfill, and does it hurt without a one-cast kill?
• How does the meter recover, and how fast?
• Does a full charge buy about 4–7 Spells? Does it run dry in a hard fight?
• What attribute keys casting, and does it pull the caster away from being strong everywhere?
• Is the overfill a story the table will remember?
• Does the source have a dry-caster poke and a starting bundle?