What You KnowThere are two different ways of “knowing” a spell. The first is simply having it in your grimoire. A mage can have an unlimited number of spells in his grimoire, of any level. Trading spells is a relatively easy matter between mages. However, it is less frequent than you might think, for two reasons. One, without study, there is no way to verify the difference between a genuine spell, and a group of unrelated squiggles on a page. So, fraud is very possible (though, angering a wizard is rarely a good idea), and mages tend not to trade with strangers for that reason. Two, scarcity drives up cost. If you are the only mage in a hundred miles who can heal a sick cow, you are unlikely to give your neighbor the spell, as it creates competition. So, mages tend not to trade with their neighbors. Hence, mages tend to assemble their grimoires from their masters, university libraries in large cities, and, most often, from the grimoires of dead mages.
The second, and generally more important, way to “know” a spell is to have it in your active spell list. This means that you have studied the spell often enough, and recently enough, to be confident you can reproduce it from memory. You can typically only cast spells that are on your active spell list. You can add one spell to your list for each rank you possess in Knowledge (Spellcraft). Mage classes also typically grant you bonus spells, which are added to this list. Unless an ability specifically says otherwise, you may not add a spell to your spell list that has a spell level greater than your caster level.
It is possible to exchange the spells in your list. You may spend 8 hours studying (taking no other actions), and make a Knowledge (Spellcraft) check with a DC equal to 15 plus the spell level of the desired spell (which must be in your grimoire already, and of a spell level less than or equal to your caster level). Success indicates that you lose access to one spell on your list, and gain access to the desired spell. Failure indicates no change. Critical failure means that, not only do you fail to add the new spell, but you lose access to the old spell as well. A critical success means that you exchange the spells in only 4 hours.
Casting as an InvocationCasting a spell, for a mage, is a very exacting process. Everything must be done exactly right, or the whole thing simply fails. This is not a pursuit for the idle hobbyist.
However, in terms of game mechanics, casting a spell as an invocation is extremely easy. The mage simply chooses the spell he wants to cast off of his list of known spells, expends the PPE, and enjoys the results. The individual spell descriptions cover things such as casting time (typically a single half action) and effect.
Sometimes events conspire to prevent the caster from doing everything exactly right. If you suffer damage of any sort during the casting time of the spell, or if you are the subject of a continuous damage effect, you must make a Concentration check to complete the spell. The DC for this check is equal to twice the spell level plus the total amount of damage received (if you are receiving damage from multiple sources, it is all resolved with one check). If you fail this check, the spell fails, and the PPE that would have been spent are lost. If you succeed, the spell is cast normally.
Casting a Spell as a RitualThe second way to cast a spell is as a ritual. This is a much longer, more involved process. However, it produces much more impressive results, generally by folding a number of meta-magic effects into the spell.
First, though, the casting is very different. Rather than a simple action, a ritual is accomplished through a complex skill check. The DC for the check begins at 200. The Effect Multiplier (see below) times the spell level is then added to this DC. The interval for the skill check is equal to the casting time of the spell as an invocation. Note that you do not need to make Concentration checks in the case of damage, as you do with invocations. However, if any outside force causes you to not be able to make a check for an interval, the ritual ends. No PPE is lost, but the ritual must be started again from scratch.
The Effect Multiplier of a ritual is a measure of the complexity added to it by the effects you wish to generate. For each effect below, the EM is noted beside it. Simply total up the EM for each effect to get the total EM for the ritual. Multiply the EM by the spell level and add 200 to get the ritual DC, as noted above. Multiply the EM by the PPE cost of the invocation to get the total PPE cost for the ritual. (If you wish to add any other meta-magic effects from feats, those effects multiply this total cost, but do not affect the DC of the ritual.) Some basic ritual effects include:
- EM 4 - Cast a spell from your grimoire that is not currently memorized.
- EM 1 – Allow other mages to contribute PPE to the spell, even if the primary caster cannot pull PPE from others.
- EM * – Apply a meta-magic feat you do not possess. The EM is equal to the EM of the feat plus 1.
- EM 3 – Give a spell with a range of “Self” a range of “Touch” instead.
- EM 5 – Attach the spell effect to an item or place, to be triggered later by a specified event. Any given item can only have one such effect attached.
- EM * - Cast a spell of higher level than you can normally memorize. The EM is equal to 3 times the difference between the spell level and your caster level.
- EM 2 - Make a spell that normally affects one target affect a number targets equal to one-third your caster level. This may be used multiple times for more targets.
- EM * – Enchant an item with the spell effect. There are a number of factors involved, which are too complicated to explain here.
- EM 3 – Ignore the range of the spell. The spell can affect the target anywhere on the same planet.
- EM 1 – Increase the save DC of the spell by 5. This may be used multiple times.
- EM 1 – Allow a spell with a range of “Self” to affect the target instead, if the target is touched.
- EM 3 – Attach the spell effect to the person, which the person can trigger at a later time. Any given person can only have one spell so attached.