For playability, Runeweaving was adapted from the Words of Power introduced in Ultimate Magic. The original system for Runeweaving was cumbersome and the Word of Power system, once modifications were made, filled the Runecasting niche quite well. The old system was abandoned for the adapted Pathfinder system.
Arranging Runes of Power
A runeweaver still has spell slots, just like other members of his class, but he uses them differently. Each spell slot holds a rune or allows a runeweaver to arrange a number of runes of power into one. The level of the runeweaver’s rune is determined by the arrangement of runes. Each rune of power has a level associated with it and, in some cases, restrictions on what other runes can be arranged in a rune with it.
The level of a rune is also the minimum level of the spell slot that can be used to arrange that rune into a rune. A runeweaver spontaneously casts spells and he can arrange his runes as he casts them. Each rune is made up of an arrangement of two or more runes of power, including one target rune, one or more effect runes, and possibly a number of meta runes.
This rune determines the range of a rune, how the rune manifests, and what it can affect. If the rune has an area, it affects every creature in the area defined by the target rune. If it has targets, it affects the specific targets described by its rune. A rune can have only one target rune.
Effect runes determine what effect a rune has when cast. They also determine the schools of the rune and its duration, saving throw, and spell resistance, if any. A rune can have more than one effect rune, even ones from different schools of magic. In this case, the spell counts as both schools of magic.
Effect runes are split into groups of similar runes. A rune typically cannot have more than one effect rune from the same group, but there are exceptions. A rune can have more than one effect rune from the Detection group, but cannot have a rune with an effect rune from the Detection group and an effect rune from any other group.
This rune modifies the rune in some way, often by increasing either its duration, range, or components. It can also boost certain target or effect runes, changing the rune’s overall effect. Unlike with other runes, a runeweaver can only use meta runes a number of times per day equal to half his caster level in his runecasting class (minimum 1). A rune does not need to contain a meta rune.
A rune can have multiple meta runes arranged within it so long as each target rune and each effect rune are modified by only one meta rune apiece. For example, a rune arranged with two effect runes could have up to three meta runes, so long as each meta rune modifies a different target and effect rune.
Casting a rune is similar to casting a standard spell. Each rune is assumed to have a somatic, and verbal component. Runes take one standard action to cast and provoke attacks of opportunity as normal unless the caster casts the rune defensively. The DC for casting a rune defensively is the same as it is for a spell of the same level. The DC for any saving throw called for by the rune is calculated the same way as for any other spell of that level. A runeweaver uses her Int to determine the rune DC.
Casting a rune is almost exactly the same as casting an ordinary spell. A rune can be dispelled and disrupted, and casting one provokes attacks of opportunity, just like any other spell, unless the runeweaver casts the rune on the defensive, which also requires a concentration check as normal. There are two major differences to casting a rune: counterspelling and schools.
If a runeweaver is attempting to counter another rune, she can make a Spellcraft skill check as normal to identify the rune as it is being cast and then cast an identical rune to counter it. This means that the opposing runeweaver must know all of the effect runes of the rune and either have an identical rune prepared or have an available spell slot of an equal or higher level. If the rune contains multiple effect runes, but the opposing caster only knows one of the runes (or only has a rune with one of the effect runes prepared), that caster can still attempt to counter the rune, but this functions as if using dispel magic and does not come with the guarantee of success. The opposing caster must make a dispel check to counter the rune. She must still expend a spell of the same or higher level containing at least one rune of the rune to be countered.
If a runeweaver is attempting to counter the spell of a normal spellcaster, she must make a Spellcraft skill check to identify the school of the spell being cast. She can then counter that spell using any rune so long as it is of an equal or higher level than the spell being cast and contains at least one effect rune of the same school as the spell. This works like a dispel magic counterspell attempt, and the runeweaver must make a dispel check to counter the spell with a -2 DC. If a spellcaster attempts to counter a rune, she must use a spell of an equal or higher level that is of the same school as one or more of the effect runes in the rune being cast. This too works like a dispel magic counterspell attempt, and the spellcaster must make a dispel check at +2 DC to counter the rune.
If a rune has more than one effect rune, it can belong to more than one school, although it never benefits from effects based on school (such as Spell Focus) more than once. It can take penalties based on school more than once; for example, if a target has a bonus on saving throws against necromancy and illusion spells, that character would add both bonuses on the saving throw if the rune is of both schools.
Rune Saving Throws
The type of saving throw for a rune is determined by the highest-level effect rune used that allows a saving throw. If the save is successful, it applies to both effect runes, but the result for each rune can vary based on the individual rune. If the save fails, the target takes the full effect of both effect runes. The save DC is equal to 10 + the rune’s level (not the effect rune’s level) + the runeweaver’s Intelligence modifier.
For example, if a 5th-level rune contains a 2nd-level effect rune that allows a Ref lex save for half and a 4th-level effect rune that allows a Will save to negate, targets of the rune make a Will save with a DC of 15 + the caster’s Int modifier. If the save is successful, the target takes half the normal effect from the 2nd-level rune and negates the 4th-level rune. If the save fails, the target takes the full effect of both effect runes.
Runes and Spell Resistance
If the rune uses more than one effect rune, and any of those runes allow spell resistance, the resistance applies to all of the effect runes of the rune. A rune only ignores spell resistance if all effect runes ignore spell resistance.
Multiple Effect Runes and Damage
If more than one effect rune causes the rune to deal damage, the total number of dice of damage the rune can deal can be no greater than the rune’s caster level. The caster can decide which dice belong to which effect rune, in any combination, so long as the total number does not exceed his runeweaver level and the number of dice allocated to a specific effect rune does not exceed its maximum.
Multiple Effect Runes and Duration
If a rune has more than one effect rune, the shortest of all the effect runes’ durations is used for all of the effect runes.
Magic Item Creation
It is possible to create magic items using the runes of power system, but since the caster meets none of the spell prerequisites, this process is more difficult than the standard method of magic item creation. This process is covered under the Runecrafting ability.