Spell crafting and a small self-contained magic system

Homebrew Toys #1

Hi everyone!

I was preparing some homebrew for a game with some friends, and I realized that maybe I could make a space here to share some of these loose ideas with you.

A bit of context: These friends are beginners, they have never played any ttrpg before we started to play together (we have played just twice). We are using Knave because they wanted to try something simple but “close” to dnd. Initially, they wanted something with “low-magic” and more horror themed and deadly. However, when we started playing, they realized they wanted to have more room to explore magic, its creation and the interaction between spells.

So I made a simple spell-crafting + magic-system for them.

Here I share with you this system with some alternative self-contained stats, in case you want to use these ideas as a self-contained system that does not interact with other parts of your game.

Alternative Self-contained stats

You can use the stats of your favourite rules-lite fantasy OSR/NSR game or, if you prefer, you can use these two arcane stats:

Cast and Resist.

The sum of Cast and Resist is 0.

The max value that any of them can have is +5.

Example: If you choose Cast +3, then your Resist is set to -3.

If you decide to use Cast and Resist you can also use these:

• HP, the amount of magical damage that your body can sustain = 10+Resist.

  If you reach HP=0 you scatter into atoms. This HP can be healed magically or as any wound.

• Spell load, the number of spells you can carry within one tome = 10+Cast.

  Spell load can be thought of as how compress and clear is your own arcane notation, being higher if you can fit more spells in the same number of pages of a tome.

Spell crafting

Spell crafting requires you to combine two spells to create a new one:

• Some spells are base spells. These spells are not created from other spells. There is a finite set of them. They can be learned by anyone who has access to them and enough time to study them. These spells can be the ones included on the list of spells of the game you are playing or the list at the bottom.

  If you are using Cast and Resist as stats:

  • To learn and understand your first base spell took you a number of years equal to your Cast (alternative can be your INT bonus).

  • To learn a new base spell takes you a number of weeks equal to your Cast (if you have a low Cast you can learn spells faster, but your casting will be more instable and prone to failure).

• Any spell that is not a base spell is built from any other two spells.

• Spells exist in layers (degree of complexity).

  • Base spells are at layer 1.

  • A spell built from 2 or mores base spells is at layer 2.

  • A spell can be built from spells from the same layer or different layers.

  • Any spell built from at least one spell from layer N is at layer N+1.

• Any spell created like this will have only 2 quantifiable effects.

• Their quantifiable effects are the min of one of the two spells and the max of the other. If they only share one type of quantifiable effect, take the one that is smaller from one spell and any other quantifiable effect from the other spell.

Example: Fireball (range 100, damage 6d6, area 30) + illusion (range 30, 1 target, 1 min) = fire-illusion (range 30, 6d6) or fire-illusion (1 target, 6d6)
In this example Fireball and Ilusion only share "range" as quantifiable effect.

• If the new spell you want to create needs another quantifiable effect (HP, number of targets, speed, volume, time, etc…) that quantifiable effect is a d4 or determined by you rolling 1d4 when creating the spell.

  When adding this new quantifiable effect, you are writing this spell in a higher layer, connected by a single line with a version of itself where the quantifiable effect value is 1. This “buffer spell” is connected to the other spell used to create the new spell.

Casting, Instability and decay

• To cast a spell you have to roll 1d20+Cast (INT/Arcana) against the DC of the spell.

• The DC of casting a spell depends on its layer → DC =10 + layer.

• When failing on the casting the spell becomes instable and decays into the spells from which it is made from, cascading all the way down to the base spells, activating all these spells with different random targets each.

Example: Fire-illusion (layer 2) → DC 12 (10+layer):
If fail the Fire-illusion decays into Fireball + Illusion with a random target each.

• Every spell takes 10 min to cast:

  • To cast it as an instantaneous spell → DC+4

    • You can cast as many instantaneous spells as you wish, one after the other.

    • For every instantaneous spell you have cast just before an instantaneous spell you are casting, its DC increases in +2.¹

  • You can take your time and cast a spell in 1 hr → DC-4

Copy spell to spell-book

• To copy a spell, you have to “disentangle it”, rolling 1d20 + Cast (or INT/Arcana) for every spell from which the spell is made from, top-to-bottom. The DC of disentangling each spell into its components is the same DC of casting the spell.

• You expend 4 hr of work per spell, independent if the attempt fails or succeeds.

• In a fail, you can’t disentangle that spell into its components.

• In success, you will disentangle the spells into the two spells that were used to create it, then you have to disentangle these new spells until you reach the base spells.

• If you reach a base spell you don’t know, you will be able to learn it in Cast weeks. You can’t cast the spell you are disentangling before learning all the base spells nested on it.

• When disentangling a spell, in a critical fail (d20=1), the spell becomes instable and decays. This does not destroy the work already done of disentangling the spell.

• Expending 2 hr of work per spell increases the DC in +4.

• Expending 8 hr of work per spell decreases the DC in -4.

Writing a scroll

• To make any spell an instantaneous and secure spell you can write a scroll of it.

• Scrolls are written bottom-to-top, every spell nested inside the spell you want to write takes 1 hr of writing.

• To write each nested spell you have to make a writing test, same DC of casting that spell (1d20 + Cats/INT/Arcana).

• In a fail the 1 hr of work is lost.

• In a critical fail (d20=1), the spell becomes instable and decays, starting from the last layer already written on the scroll. This does not destroy the work already done of transcribing the spell into the scroll.

• Any spell on a scroll can be cast as an instantaneous spell without any penalty to the DC.

• Expending 0.5 hr of work per spell block increases the DC in +4.

• Expending 2 hr of work per spell block increases the DC in -4.

• Once the scroll is used, it disintegrates into dust.

Save against spell

• When being the target of a spell you can save against it, resisting its effect.

• To save against a spell you have to roll against the DC of casting the spell (d20+Resist/WIS vs DC)

Counter spell

• When witnessing a spell in mid-casting, you can try to counter-spell it by identifying the base spell entangled on the magical theorem being spoken, gestured, or invoked.

• To identify the base spell inside a spell in mid-casting you have to roll Cast (INT) against the DC of the spell.

• To interrupt a spell you need to cast as an instantaneous spell any of the base spells you identify into the target that is casting the spell.

Base spells

Alacrity: Increase the speed of anything you touch (speed x2, touch, 1 min).

Animate: You can animate a small object, they will follow your command (touch, 10 min).

Blink: Every 6 seconds you blink out of existence for 6 seconds (1 target, 1 min)

Bond: You can bond yourself to another being, you share thoughts, feelings, and learned skills. (range 30, 1 target, 10 min)²

Command corpse: You can puppeteer a corpse no larger than a big horse (range 60, 1 dead being, 1 min)

Control water: You can make water take any shape you want (range 30, volume 10, 10 min)³

Darkness: You can invoke a sphere of deep magical darkness (range 30, volume 30)

Detect magic: You can sense the presence of magic (range 30, 1 min)

Enlarge: You can make something grow (size x2, touch, 10 min)

Fireball: You can shoot from your fingers a spark that will detonate into a large infernal ball of fire (range 120, area 20, damage 8d6)⁴⁵

Flesh shape: You can mould flesh as if it were clay (touch, volume 1)

Friend: You can make someone think you are an old friend they haven't seen in a while (range 30, time 1hr)

Force wall: You can conjure a wall made of magical energy (range 5, area 5, 1 min)

Gust: You can make air move, triggering a strong wind (range 5, volume 20, 1 min)

Illusion: You can translate into any image whatever you imagine in your mind’s eye (range 30, area 10)

Light: You can make something glow as if it were a torchlight (range 10, area 20)

Lighting: You can command the sky to make lighting strike the ground (range 60, damage 3d10, area 30)

Mend: You can repair anything that was handmade (touch, area 1 inch)

Multiply: You can make a copy of something (touch, non-living creatures, x2, 1 min)

Plane compass: You can sense the presence of any fracture that opens toward other planes of existence (range 1000, 10 min)

Psychometry: You can sense what happened around an object as being there, you experience everything backwards, starting from the moment you touch it (touch, 1 hour)

Restore life to plant: You can make a dead plant come to life (touch, 1 target)

Shrink: You can make anything shrink twice its size (size /2, touch, 1 hr)

Silence: You can force absolute silence into a sphere (range 20, volume 10)

Slow: You can make anything move ten times slower (speed /10, touch, 1 min)

Stone shape: You can shape stone as if it were a soft clay (touch, volume 5)

Telekinesis: You can slowly move with your mind anything that weights 40 pounds and fast anything much lighter than 40 pounds (range 30, weight 40 pounds)

Telepathy: You can read the surface thoughts of anyone and speak to their mind (range 60, 1 target)

Teleport: You can banish and reaper in other point in space (range 1000, self)

Transmutation: You can transform any material into any other material you know (touch, volume 1).

Keen sense: You can enhance one sense ten times fold (touch, enhance x10, 1hr)

1. I used this to give more room for “magic duels”.

2. All distances are in feet.

3. The value beside “Volume” is the radius of the sphere in which volume the spell has its effect.

4. All spell damage is magical. If you are using the alternative self-contained magic system, the damage from spells reduces HP.

5. The value beside “Area” is the radius of the circle in which area the spell has its effect.