A orange ioun stone adds +1 caster level, what does this affect?

  • Damage from spells? (Like fireball)
  • Duration and area of effect?
  • "Amount" of effect (Like number of missiles from magic missile)
  • Spells known by a wizard (ie +1 caster level mean a level 2 wizard gets the spells as if they were level 3?)
  • Anything else?

4 Answers 4


In 3.5e, caster level affects (as its name suggests) caster level checks for dispelling a spell, or overcoming spell resistance. Also, caster level may affect the following variables in spells:

The list is not exhaustive, and some or all of the properties mentioned above are not changed for certain spells. (e. g. Cantrips are not dependent on caster level, and many spells like fireball don't have area change per caster level.) In general, caster level changes anything with the phrase "per (caster) level" in the spell description, and caster level checks.

It never affects:

  • Spells known by the caster
  • Spells per day
  • Any other class feature dependent upon class level (Familiar benefits, bonus feats, and so on)
  • \$\begingroup\$ Would it also affect concentration checks? \$\endgroup\$
    – Rob
    Commented Apr 17, 2015 at 10:37
  • \$\begingroup\$ @Rob To my knowledge that's a change in Pathfinder and does not apply generally to concentration in 3.5. d20srd.org/srd/skills/concentration.htm for reference. \$\endgroup\$
    – joedragons
    Commented Apr 17, 2015 at 15:47

In pathfinder caster level affects the following:

  1. Effects of a spell (duration, damage, area, range, ect...) [This varies by spell]
  2. Caster level check to overcome spell resistance
  3. Caster level use in dispel magic check
  4. Concentration check



The caster level entry in the SRD you reference states

In the event that a class feature or other special ability provides an adjustment to your caster level, that adjustment applies not only to effects based on caster level (such as range, duration, and damage dealt), but also to your caster level check to overcome your target's spell resistance and to the caster level used in dispel checks (both the dispel check and the DC of the check).

Unless I'm reading it incorrectly, that looks like that is all it affects; otherwise, it would mention the additional areas it affects in any given spell, effect, check or action's entry.

  • \$\begingroup\$ This answer is missing 'concentration checks' used in pathfinder. \$\endgroup\$
    – Colin D
    Commented Jan 21, 2014 at 17:17


This seems to be a hot topic in a few places. Honestly it is simple if you read the descriptions in the source for the effective modification.

There are Three different types of ECL that can effect a caster: Effective Character Level bonus, Effective caster level after determining Spells per day and known, Effective Caster Level before determining spells per day, known and caster level.

+ Effective Character Level - This is exactly what it says, you have a boon, effect or PRC that is granting you the next step on the class table, bab, saves, specials, spells per day, known and power level(caster level).

+ Effective caster level after determining Spells per day and known - This increase the power, durations, effects, DC of spells, but does not grant you additional spells or higher level spells. This would be the common effect of a ring or amulet or item, although some other things like feats, and PRCs may do this also.

+ Effective Caster Level before determining spells per day, known and caster level - This is common with PRC class benefits. You do not gain the BAB, Saves, or specials for your caster class. You do gain level of spells you can cast, number of spells per day and spells known at the appropriate effective caster level, and casting level increase. An example of this is the Mystic Theurge, ref pp387,388 Pathfinder Core Rulebook,

"adds the level of mystic theurge to the level of whatever other arcane spellcasting class and divine spellcasting class the character has, then determines spells per day, spells known, and caster level accordingly." The text is clear. There are a few PRCs that make exception to this, but for the most part those are Homebrew PRCs, but as a rule this is how the "+1 level of/to existing" works in any PRC.

This said, remember your GM/DM has overriding privileges in the running of their world, so if they give you a house rule that is disparaging to books and guidelines, it is their world, try and keep ruling debates off the table as more private discussions. Do not lose gaming time for you or others to debate rules. ~~~~


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