Open Sorcery: Non-vancian magic for OSR games

23 Jun, 2025

Some shitty little rules for casting spells while keeping the feel of magic being deadly and dangerous. This post is mainly a middle finger to my past self for making magic too annoying to mechanize. Focuses on Leveless spells. Inspired by Luke Gearing's Magic rules for Wolves Upon the Coast and the magical rules of B. Strejcek's Wonder and Wickedness.

Casting Spells

After completing a spell's required procedure, the Magician makes a Save vs Magic or Equivalent. This is called a Spell Check.

• If the Spell Check succeeds, the Spell manifests and the effect takes place.
• If the Spell Check fails, the Spell fails to manifest.
• If the Caster rolls or has their roll reduced to a 1, then the Spell Backfires, and either creates a Mishap (incorrect casting of the spell) or Mutates the caster, up to Ref.

Afterwords, regardless of the effect, the caster incurs a multicast penalty. This will reduce spell checks for that spell by 1, going up each time the Magician casts said spell. To give a Spell Check a positive modifier, there are 2 ways of going about it:

The first method is the easiest: Going above and beyond the spell components (ie, a spell requiring bat guano but using dragon guano instead). If this is the case, the spell gains a bonus equal to the difference between whatever monsters HD (for example, a Dragon has 10HD and a Bat has 0, therefor the bonus to the spell would be +10).

However, doing this is not without its risk. Doing a spell with more powerful ingredients incurs a Coinflip. If the casting player calls incorrectly, then the spell immediately backfires.

The second method is Sacrifice. There are 2 ways of going about Sacrifice:

• Sacrificing Others, in which the bonus to the spell check is equal to the Sacrifice's HD.
• Sacrificing The Self. To sacrifice the self, the caster may sacrifice 1 point of their total HP or 1 point from their Ability scores to incur a +1 bonus to a Spell Check.

Learning Spells

Depending on how a Magician learns their spell, it takes a different amount of ways to study

• Studying By Themselves: The magician spends 2d6 days and 1,000 XP's worth of reagents. After the Study Time is complete, they make a Spell Check, learning the spell on a Success and Needing repeat the study on a fail.
• Studying With an Instructor: The magician spends 1d8 days, with the amount of days being modified by the difference between HD of the Instructor and Student. Same procedure applies as with above.
• Learning Instantly: The magician must make a save or they are stunned for 2d6 days. After it's done, they instantly learn the spell. Reversed spells count as different spells than their base variant, and a non-specific spell (ie, Polymorph) counts as different kind of spell for each specific effect. If a caster knows a reversed variant or spell of similar function, they gain a +1 to the spell check when learning said spell.

Tradition

As with the previous post, Tradition decides two things:

• Spell Preparation: The steps taken before a spell is cast (for example, in the Vancian tradition, the preparatory steps before a spell require the Magician to commit the specific spells they want to cast into their mind beforehand).
• Spell Casting: What/How the magic is cast (using Vancian magic again, the magician instantly fires out the spell, however the spell is lost and they cannot cast it again).

Rituals

Spells may also be cast as rituals. A ritual will take 10 Minutes (or whatever the length of a Dungeon Turn is in your game), with every person in the ritual making it take another 10 minutes. The upside with rituals, however, is that they will gain a +1 modifier to the check for each person in the ritual, including the Caster.

Covens, Cabbals, and other Magical Boybands.

When casting a non-ritual spell with people who also know that spell, the other Magicians can help cast the spell, which adds +1 to the spell check per each additional person. However, if a caster does this with more people then their HD (for example, a 3HD caster using magic with 4 or more other magicians), it will incur a coin flip as per Boosted Ingredients.

Counterspelling

If an opposing Magic-User casts a spell, the other Magician may intercept with a counterspell. To counterspell, a Magician must meet one of 4 prerequisites: 1: The countering spell is a reversed variant of the spell being Cast (for example, casting Light at Darkness). 2: The countering spell is a spell of opposite function (ie, Shield being cast at Magic Missile) 3: The spell is of thematic opposition (ie, Reverse Gravity at Flight) 4: The caster simply uses the same spell that the other caster is using.

To counterspell, the Magician takes the result of the targeted spell check and treats that as the difficulty of the spell check. Counterspells occur before a spell effect is determined. Depending on the results of each check, consult the table below.