Ritual Magic

[talysman]

Ritual magic is just magic that takes longer than normal magic. Use the same spell list as normal magic, but treat casting time as minutes instead of turns; if the casting time is already in minutes or longer, it's already a ritual magic spell.

The big question is why anyone would want to do this. Most settings with ritual magic give it one or more of the following benefits:

Shared cost with others: Using the number of ritual celebrants involved, look up the multiplier on the mass combat chart and divide the total hit point cost by the multiplier; each participant in the ritual loses that amount of hit points, while the leader of the ritual loses twice that. All participants must either know the spell (be high enough level to cast it) or be instructed on their role in the ritual by someone who knows the spell.

Sacrifices: Willing or unwilling victims can be maimed or slain as part of a ritual; hit points of damage are deducted from the total spell cost before figuring the shared cost. GMs might allow similar deductions for other kinds of sacrifice, like body parts from magical beasts or dust from ground-up gems.

Tweaking spells: Ritual spells can have their range, area of effect, or duration tweaked. Doubling the range or duration doubles the hp cost. Doubling the casting time halves the hp cost. All the large-scale magic, like creating a Wall of Thorns around a palace (a la Sleeping Beauty,) is ritual magic. If this rule is in effect, drop the Permanency spell, or any other spell that extends time, range, or area of effect; instead of permanency, tweak the spell to make it last for a very long time, like a century.

Pushing the limits: Magi can cast spells beyond their level limit if they have a written description of the spell (this lets you keep the iconic wizard's library without requiring memorization of ordinary spells.) Since they are normally unable to cast such a spell, there's a penalty: the mage must make a roll against a DC of 10 + spell level to successfully cast the spell, and the hp cost is doubled. Some settings might also allow non-magi to cast/lead in the casting of ritual spells from spell books: treat as a mage casting a spell beyond their level, but double the DC and triple the base hp cost.

Eldritch magic: ritual spells can even be higher than 9th level. For example, a Sleeping Beauty spell would would be a Wall of Thorns (assuming 4th level spell, equivalent to Wall of Fire) combined with Sequester (7th Level) for a total spell level of 11th; cost is 46 hp, further modified by spell tweaking.

The places where ritual magic actually impacts the game are:

Prep before the next chapter of an adventure: If, for example, the party needs to follow an aquatic monster into the depths of a lake, having the mage cast Water Breathing on everyone would leave him depleted. If there's plenty of time, handle it as ritual magic and charge everyone a small amount of hp instead.

NPC rituals: If the NPCs are casting a horrendous spell, you can do a quick calculation to see how long the total spell should take. Set that as the time limit for the PCs to make it through the dungeon in an attempt to stop them. Or, calculate the hp cost and make a roll to see how far the cultists made it through the ritual before the PCs interrupted; this tells you how much hp they have already lost before a combat begins.

Scrolls: Mages can write the instructions for any spell they know, although none would need to do so, except to create an item for sale/trade or to provide a tool for low-level hirelings to carry out their command ("Go to the east wall of the Sealed Tomb and read this Passwall scroll.") Ordinary spell scrolls are treated like ritual magic: anyone can read one in one minute's time and pay the spell cost. The scroll is reusable.

Mages can also enchant a scroll to store some or all of the energy of a spell. Treat this as a 1st level spell, Enchant Scroll, that combines with whatever spell is actually in the scroll to act as a trigger to release the energy. The reader of the scroll must still successfully cast the spell and pay any remaining hp cost (minimum of 1 point.) Enchanted scrolls crumble to dust when used.

[Slortar]

I like this.  A lot.

I could also see this being useful for campaigns where people can't normally cast spells, say in mordern horror.  I suppose that would fit under the section on "pushing the limits".

[talysman]

I like this.  A lot.

I could also see this being useful for campaigns where people can't normally cast spells, say in mordern horror.  I suppose that would fit under the section on "pushing the limits".

Yes, exactly. I was thinking of possible M20 Call of Cthulhu (Why not? There was a d20 CoC...) Or at least a fantasy cross-over. So I included spell-casting by non-magicians as a possible option. I kind of like the idea that anyone can do magic, but magi are simply much better at it.

I thought a little bit more about this. Some of the spell-tweaking numbers might become unmanageable, so rather than have a straight "doubling the duration doubles the hp cost", it might be better to convert the duration/range modifier using the mass combat chart as a guideline. Thus, doubling the duration still doubles the hp cost, but a duration x32 spell only multiplies the hp cost x6. This lets you skip the actual multiplication and figure out how many ritual participants you need (otherwise, energy costs would rise faster than the energy savings for multiple participants.)

[JSpektr]

Here are the very simple ritual magic rules I wrote up a couple of months ago and posted on rpg.net. My preference is to keep things as rules-lite as I can.

Rituals:

Any spell can be cast as a ritual, including spells in scrolls or books the caster does not know. To cast a spell as a ritual, the caster spends 10 minutes performing the ritual, and makes a magic roll. If the roll is successful, the hitpoints requires to cast it are reduced by 2. The caster can continue the ritual and make a new roll every ten minutes at a cumulative -5 to lower the spell cost by another 2 hp.  If a roll fails, the ritual ends and the caster must cast or abandon the spell. Two casters with knowledge of the same spell, or access to the same written spell, can cast a ritual together, both contributing hps (in any combination) to the spell total, and both lowering the cost with each successful roll.

Sacrificial Rituals:

If an intelligent being is sacrificed as part of a ritual, their hitpoints may be subtracted from the spell cost. If the sacrifice is willing (and not magically compelled or blackmailed), double their hitpoints may be subtracted. Unintelligent animals or creatures only contribute 1/4 of their hitpoints. Casters may sacrifice themselves as part of a ritual. A sacrificial ritual takes a minimum of 30 minutes to perform (taking longer reduces the cost per regular rituals).

A simple way of working in the tweaking idea would be to allow the spell cost to double to double the effects of the spell. Or triple for triple, etc.

Because this allows casters to both cast spells they don't know from books, and to lower the costs enough to cast spells they normally don't have enough hps for, it models NPC spellcasters dabbling in forces beyond their control nicely.

[talysman]

@ JSpektr:

I might have to rewrite my rules to be shorter and clearer, since basically, they're the same as your rules, except I only have one skill roll (and only if the ritual leader doesn't know the spell) and use the mass combat rules to simplify math. They just look longer! I guess I was trying to be too thorough in my description.

The mass combat application is probably what makes my rules seem more complicated. Maybe a restatement of that?

"Treat ritual magic by a group as if it were mass combat, with a Casting Scale determined in the same way as Combat Scale. Divide hp cost for the spell by the Casting Scale to find the hp cost per participant; double the cost for the ritual leader. Doubling range, duration, or some other measurement in a spell lowers CS by 1; doubling casting time adds 1 to CS. Sacrifices or maiming subtracts from the hp cost of the spell."

I think that's a pretty good condensation of the Shared cost with others, Sacrifices, and Tweaking spells sections for my first draft. The Pushing the limits and Eldritch magic sections could probably be summed up in a few more sentences.

"If the ritual leader does not know the spell, make a magic attack roll against DC 10 + spell level. Double the DC if casting a spell of the wrong class. This also adds +1 to CS (+2 for wrong class.) Spell effects can be combined by addling spell levels; ritual magic spell levels can go beyond level 9."

There are a few other differences between my rules and yours, but they could mostly be considered setting differences (shorter casting time, no bonus for willing victims, etc.)

[talysman]

I think if I write out more detailed examples, I'd need to talk about Spell Scale. Spell Scale is just the Casting Scale (CS) you'd need to cast a modified spell without having to modify the cost of the spell.

Example: Floating Disk is a 1st-level spell. It would normally cost 3 points to cast and creates a 3-foot diameter disk. If a caster wanted to create a 30-foot diameter disk with ritual magic, the Spell Scale is x4; the caster could either spend 12 hp or get 5-9 assistants, to get the cost back down to 3 hp.

Most of the time, you assume a Spell Scale of x1 and just directly modify the Casting Scale, decreasing it by 1 every time something doubles, increasing it by 1 every time you double the time. But if the Casting Scale gets down to 1, any further improvements to the duration, range, or other spell effects increases the Spell Scale instead.

Another fancy use of ritual magic is dispelling or modifying an attachment. If you use this option, Dispel Magic only dispels ordinary spells and temporarily suspends enchantments. To permanently disenchant something, you recast the spell and modify its duration. This can also be used to extend existing enchantments, move them, or otherwise alter them.

You could retell the story of Sleeping Beauty as a battle between two powerful fae enchanters modifying each other's enchantments: the evil fae curses the princess with death when she hits puberty, the good fae for unknown reasons is unable to completely dispel the curse, but she's able to modify it to sleep for a hundred years at puberty, then the evil fae (again, unable to completely dispel the magic) modifies this to affect the whole kingdom, the good fae inserts a condition that allows a hero to end the spell, and the evil fae attempts to block the hero by adding a barrier of thorns.