Based on Incantations from Unearthed Arcana, ritual magic permits powerful spells to appear in the game in dramatic and interesting ways, without being quite as common and stress-free as normal D&D magic.
Anyone can perform ritual magic, so long as they know what to do. And in some cases, a character can fake it and something may happen -- though not necessarily what is desired.
A character can take a ritual knife, go out into the moors on a full moon, cut his arm while calling on the forces of darkness to take his ex-lover. And the ritual may work...
Learning a rite allows a character to understand the basic structure of casting the spell and, reasonably, what to expect. This requires a Knowledge (arcana), Knowledge (religion), or Knowledge (nature) check, though sometimes Knowledge (history) or Spellcraft may be allowed. DC is 15 + spell level (or approximate, for effects that don't fall neatly into a particular spell). The effort takes 1 day, and cannot usually be retried; if the character learns something new about the ritual he may try to learn it again.
Once learned, the character may attempt the ritual, but at +5 DC. If the character has not performed this ritual before, the results may be surprising.
Characters may learn any number of rituals.
To be performed properly, a ritual must be mastered, which requires the ritual magic feat. With a mastered ritual, the character has a reasonable expectation of what the ritual entails, casts at the normal DC, and can tweak the ritual into alternate forms.
Mastering or changing a ritual requires similar skills as learning the ritual, but DC is 20 + spell level. It takes 1 day, and may be retried indefinitely.
Only a few rituals can be mastered at a time (3 with ritual magic, 6 with ritual magic and ritual mastery).
Mundane works are treated like ritual magic, but are not actual magic. Instead, they are incredible achievements of skill. While the effects are more limited, the consequences of failure are similarly more limited.
A ritual requires a number of skill successes equal to its skill level, with DCs starting based on spell level (and then subject to a number of modifiers). Each check takes 10 minutes. Most rituals of 2nd or higher level use multiple skills, worth -1 or -2 DC. Ritual skill checks may not benefit from Aid Another (but see Helpers).
Rituals have at least 1 point of toll, and often more. Toll is the strain or price of casting magic, the effects of which kick in when the spell is over (whether successful or not).
Rituals can be interrupted (intentionally or not), exacting toll but no further ill effects.
If there are two failures in a row, the spell fails spectacularly and triggers backlash; each ritual has particular types of backlash that are likely to occur. Generally the backlash is consistent with the attempt of the ritual, and has a power equal to the spell level of the ritual -- that is, a spell effect is generated, just not the one the ritualist wanted.
A ritual may permit or require helpers, additional casters who shape the magic. These helpers may provide skill checks toward the ritual, which can be very helpful if the ritual requires a number of unusual skills or diverse skills. Even if helpers don't provide direct skill, their presence can make a ritual easier to control.
Helpers are also affected by the toll of the ritual, and are often affected by backlash.
A ritual starts with a spell, or an effect judged to be at a given spell level. Exotic metamagic may apply, but adjustments to range and duration should be handled by effect modifiers (below) or eyeballing higher spell levels.
Base ritual DC = 20 + 2/spell level
Effective caster level is 2x spell level.
Spell Save is 10 + spell level + minimum ability score modifier that could cast spell or primary caster's modifier (whichever is higher)
Effect modifiers DC modifier
Touch to close/close to touch +2/-2
Close to medium/medium to close +2/-2
Medium to long/long to medium +2/-2
Double area/half area +3/-3
Rounds to minutes/minutes to rounds +2/-2
Minutes to hours/hours to minutes +4/-4
Hours to days/days to hours +6/-6
Days to permanent or instanteous/ +10/-10
permanent or instantaneous to days
Limitations DC Modifier
All rituals are specific, limited forms of spells. If a spell has several options, the ritual does only one option. Rituals are also often limited to a particular place or context.
Can only be cast rarely (full moon) -4
Very limited cast time (winter solstice) -8
Unwilling target must be helpless -2
Limited target (by HD, creature type) -3 (possibly more, if very limited, like 'redheads')
Single target to multiple targets +4
Note that limited target can't be adjusted, and is considered part of the basic ritual.
Cast modifiers DC modifier
These can help moderate the difficulty of casting ritual magic.
1 hour per skill check -1
Extra skill needed -1 per extra
Some skills needed are unusual (Perform (drums)) -1
Some skills needed are rare (Craft and Profession) -2 (includes unusual)Material components (500g) -1
Expensive material components (5000g) -2
Fairly expensive material components (15k g) -3
Very expensive material components (25k g) -4
Expensive focus (5000g) -1 (reusable, but specific to ritual)
Very expensive focus (25k g) -2
1-3 Helpers (modifier is sqrt of # of helpers, max -11) -14-8 Helpers -2
9-15 Helpers -3
Toll DC modifier
2d6 damage, 1 ability score damage (either spellcasting score or Con), fatigue -1
Exhaustion, temporary negative level -2
Reduced to -1 hp -3
Infected by disease -4
Dead (and this form of death cannot be evaded) -5
Weaving is a form of magic practiced by thaumaturges. It is similar in several respects to ritual magic and is calculated in similar ways.
The effects of weavings are more limited than those possible in rituals. Weavings cannot create, heal, or dramatically transform. Summoning monsters and animals is only possible as an effect of binding into service existing monsters or animals that are on hand, such as seeing a wolf and 'summoning' it.
A weaving takes only one full round action to perform each skill check, rather than 10 minutes.
Weaving is limited by the art level of the thaumaturge and by the thaumaturge's caster ability score, caster level and spell saves are calculated based on the thaumaturge only.
A thaumaturge is considered to have mastered any weaving that falls within her focus, and gains a further +2 to perform such weavings. Weavings that fall outside her focus, but are still considered part of her path of magic, can be performed as learned but not mastered weaving -- such attempts are at +5 DC and there is no bonus to cast them.
Any effect that falls solidly outside the thaumaturge's path of magic (such as charm animal for an elementalist) cannot be woven -- the thaumaturge must use true ritual magic, instead.
Skills used in a weaving are specific to the thaumaturge. Each weaving must start with an understanding skill success (which skill is particular to the thaumaturge, though sometimes may vary a little). 2nd and higher level weavings must then have a shaping skill success. After that, the thaumaturge may use either skill. 2nd and higher level weavings, thus, have the -1 DC modifier for extra skill use.