Tome of Prowess (3.5e Sourcebook)/Arcana

Arcana

The Arcana skill is a reactive skill. It allows you to determine the weaknesses of construct, dragon, and undead creatures as well as to identify arcane magic effects. Characters with substantial training in Arcana can even ignore attribute requirements on magical items. It is an important skill for arcane spellcasters, as it allows them to cast their spells while threatened without leaving themselves open.

Key Attribute: Intelligence

Untrained Uses

None. Sorry, you actually can’t do this stuff without a bit of training.

Rank 1 Uses

Creature Insight

You’ve picked up about some knowledge about some of the most common arcane creations and allies, namely constructs, dragons, and the undead. Constructs are creatures built of material that have been animated by magic bound to their frames. Dragons are mighty scaled beasts that live amongst the highest clouds and down in the lowest deeps, and carry a great many arcane secrets. The undead are the remains of once living creatures, animated to continue walking and working even after their bodies have given out. As an immediate action, you can attempt to identify a creature you are facing. The DC for this check is 15 + the creature’s CR. The creature does not have to be alive for you to try to gather information about it, though deceased creatures need to be largely intact.

Special: The arcana skill only allows you to identify undead and constructs, and there are several other skills that provide similar knowledge for other creature types. If your GM is a nice guy, he’ll just tell you which skill you need to roll to gather information about a creature. As this may reveal more information than they want, they may not tell you which skill you need. In that case, only roll once for all skills; just add your modifier from each skill to your roll and give him all 5 results separately.

Base DC: 15 + the creature’s CR
Check Result

• DC+10 and above: You correctly guess everything in the lower success results, as well as every other special quality and attack that the creature has. In a less serious game, you can just ask the GM for their notes and read up on it while everyone else gets into position.
• DC+5 to DC+9: In addition to the information learned from a basic success, you also correctly guess 3 special attacks or qualities of the creature. These are either determined randomly from those you have not yet witnessed or you may ask for further details on one you have witnessed (type of DR if you have witnessed it, type of breath weapon, etc.).
• DC+0 to DC+4: You correctly guess the creature’s type, subtypes, and any traits that would come as a result of those categories. If the creature is sufficiently common you also know its name, and that may provide other information.
• DC-1 and below: You are unable to reach any conclusion that you are happy with. You can not retry this check until you witness one of its special abilities or qualities first hand; sometimes getting bathed in acid jogs a memory.

Identify Magic

When you run across magic, it’s nice to know if it’s magic that will help you or flay you alive. The Arcana skill primarily deals with the esoteric magic of wizards, though it can be used to identify spells or effects from any source. The various uses of this skill include identifying a spell as it is being cast, identifying a standing magical effect, identifying magical residue after an effect ends, etc. You must have detect magic active or possess an etheliometer to learn anything with this ability. The action required depends on which of these two methods you use.

Special: This ability is specialized for a particular aspect of magic, and may not be the best skill for you to use to learn about a particular effect. If your GM does not specify which skill you need to roll, and they are well within the rules not to, only roll once for all skills; just add your modifier from each skill to your roll and give him all 3 results separately. Your GM is responsible for making sure that you get the largest applicable bonus and applying it to your check to learn about an effect, and you should beat him about the head with this book if he willfully fails in that task (note: do not actually do that, it’s impolite).

Base DC: 15 + twice the effect’s level or 15 + caster level for non-level effects, +2 for each degradation period passed since an effect ended
Check Result:

• DC+5 and above: You learn the same information as on a regular success, but you learn it for divine and natural magic effects as well.
• DC+0 to DC+4: If the magic is arcane you learn its school, subschool (if any), caster level, and spell level (if applicable). You learn the name of the spell for any effect 2 levels lower than the highest you can generate, and for any effect of any level if you would have reason to know of it (stories, commonality, can cast it yourself, etc.).
• DC-1 to DC-5: You recognize the type of magic (arcane, divine, natural), but nothing further. Additional checks may yield more information.
• DC-6 and below: You do not recognize this effect and understand nothing about it. Additional checks may yield more information.

Defensive Casting

Casting in combat is difficult, since making sure that you cast the spell right often means that you leave yourself open for a moment. It takes focus to do both, and the more deeply you understand your magic the more easily you can do so. As part of the action to cast an arcane spell, you can attempt to cast it defensively. This check is rolled once, and the result used against the DC for each opponent threatening you in melee. The DC for each opponent is 10 + their BAB or twice the spell level, whichever is greater. The DC increases by 1 for each person beyond the first who threatens you.

Base DC: 10 + twice the spell level or 10 + opponent’s BAB, whichever is greater; +1 for each person beyond the first that threatens you
Check Result:

• DC+0 and above: Your casting of the spell does not provoke an attack of opportunity from this opponent.
• DC-1 to DC-5: Your casting of the spell provokes attacks of opportunity from this opponent.
• DC-6 and below: Your attempt to keep yourself covered backfires. Not only does your casting of the spell provoke at attack of opportunity from this opponent, they gain a +3 bonus on the attack.

Rank 4 Uses

Ignore Attribute Requirement

Arcane magic is based on tricking the world into doing what you wanted it to do all along, and some of those tricks work to coax magic items into working for you even when you lack the prerequisite attributes. If a magic item requires a certain ability score to function, you can try to ignore that requirement. The DC for this check is 15 + the minimum required ability score. If you succeed on the check, the item functions as if you have the minimum required ability score. If the item requires additional skill checks to activate, both of these checks are made at the same time, so you are bound to the results of this check upon activation.

Base DC: 15 + minimum required ability score, or 15 + caster level
Check Result:

• DC+10 and above: The item functions as if you had an ability score 6 points higher than the minimum required to operate it. Nice job.
• DC+5 to DC+9: The item functions as if you had an ability score 2 points higher than the minimum required to operate it.
• DC+0 to DC+4: The item functions as if you had the minimum required ability score to operate it.
• DC-1 to DC-5: The item fails to function.
• DC-6 and below: The item fails to activate, and you suffer 2 points of attribute damage to whichever attribute you needed to activate the item. The item becomes inoperable for 3d6 minutes.

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