There are a fair few spells that have more powerful results with a higher Caster Level. Magic Missile creates more missiles, Fireball uses more damage dice, Cure spells restore more hitpoints, etc. In addition, any spell that can be resisted/countered/dispelled uses Caster Level to determine how likely this is to happen.
But I'm unclear where exactly this caster level comes from. Lets take Magic Missile as our example. It is a first level spell, so as a level one wizard I can prepare it in a first level spell slot just fine. But once I become a fifth level Wizard, get a caster level of three and have access to third level spell slots, I'm not sure what happens.
If I prepare Magic Missile in a first level spell slot, does it get its second missile because I personally have Caster Level three, or does the spell itself need to be in a third level spell slot to be considered a Caster Level three spell? Or is it some third thing I'm just unclear on?
Best Answer
Spellcasters and “levels”
The word “level” is notoriously overused in D&D, and therefore also in Pathfinder. Characters have many, many different “levels” relevant to them, and yet in almost all cases things use the word “level” without any clarification.
Character level is your overall level, which is also equal to the number of “hit dice” you have, so “character level” and “hit dice” are used interchangeably. This is what is used for your total hp, your bonus to total hp from Constitution, your skill points, your maximum skill ranks, when you get feats and ability score improvements, and various other things besides. For a typical single-classed “player race” character, this is equal to class level and effective character level.
Any time a feat uses “level” without specifying something else, it’s referring to your overall character level.
Class level is your level in a given class. You can have multiple of these, if you are multiclassed. The phrase “{class} level” means your class level in {class}, e.g. “wizard level” is your class level in the wizard class.
Any time a class feature description uses the word “level” without specifying something else, it means your class level in that class.
Caster level is, in a sense, how good you are at casting spells. For most spellcasters, it is equal to their class level in the class that gives them spells—until you start adding bonuses to it from items, feats, and so on. And some classes say your caster level is equal to half your class level (so-called “half-casters,” like paladin or ranger). A 5th-level wizard has caster level 5th, unless he has a bonus for some reason, while a 5th-level paladin has caster level 2nd, again unless she has a bonus for some reason.
Importantly, even though your base caster level is (for most spellcasting classes) equal to your class level, they are not the same thing. Bonuses to caster level don’t improve anything else about your features from that class. That means caster level bonuses do not improve your spells per day, spells known, or maximum spell level. Those bonuses only increase your caster level, which makes the spells you cast stronger, but do not allow you to cast more or stronger spells.
Whenever a spell’s descriptive text refers to “level” without specifying something else, it’s referring to your caster level for the class whose spell slots you’re using for the spell. Typical uses of caster level include the spell’s range, duration, damage, and resistance to dispelling.
Spell level is a measure of how hard a spell is to cast, which is mostly related to how powerful a spell it is, and how difficult it is to resist. It is the level used for calculating the spell’s saving throw DC, and also the level that interacts with some spells like globe of invulnerability and spell turning. The Heighten Spell metamagic feat can be used to increase this value for the sake of those calculations, though usually it’s better to just use a higher-level spell.
The Level section of the spell statblock lists what spell level the spell is at for each class that can cast it. See the dispel magic description, which has
That’s saying that dispel magic is found at 3rd level on a whole bunch of spell lists (“domain” and “subdomain” refer to cleric class features that give access to small lists of spells, “bloodline” refers to a sorcerer class feature that does likewise, and “elemental school” is an optional wizard class feature that gives extra spell slots that can only be used for spells on those lists). Notably, the inclusion of “druid 4” which indicates that on the druid spell list, unlike all the others, dispel magic is a 4th-level spell. Because of this, it is impossible to say that a spell is any one level—it can have different levels for different classes, or even within one class (for example, a cleric domain might have a spell also found on the cleric spell list, but available at an earlier level than it is for most clerics).
Aside from the Level section of the spell statblock, text will use “spell level” to refer to spell level. The word “level” in a spell’s description text is for caster level, not spell level.
“(Effective) spellcasting level” or similar is not a term found in the game rules, but used sometimes in online discussions. This is because some prestige classes “stack with” or “count as” levels in a spellcasting class for determining your caster level, spells per day, spells known, etc., but not anything else about that class. For example, a 7th-level wizard/3rd-level loremaster has class level 7th in the wizard class (and so non-spellcasting wizard class features that refer to “level” use 7), but has the caster level and spells per day of a 10th-level wizard—because the 3 levels of loremaster count for that. That means, like a 10th-level wizard, this loremaster can cast 5th-level spells—which a 7th-level wizard cannot do. So using “spellcasting level” or “effective spellcasting level” or something like that can be convenient for describing someone who has the spellcasting of an Xth-level wizard, even if they do not actually have X class levels in the wizard class.
Note that this is different from just “caster level.” Prestige classes like loremaster improve caster level, but also improve spells per day, spells known, and so on. This is much, much more than bonuses to just caster level do. For example, a 7th-level wizard who somehow has a +3 bonus to caster level uses “10” in various calculations in spells to determine range, duration, damage—but they still don’t have 5th-level spells, they still use the spells per day of a 7th-level wizard. Hence the need for a separate term, because the difference is very important.
You personally have caster level 5th, your level in the wizard class, not 3rd, which is your highest spell level, and yes, your magic missile, which you still prepare in a 1st-level spell slot, automatically benefits from your caster level 5th and so has three missiles.