The Master Caster

[TheGeometer]

Getting a ridiculously high CL is one of the most basic ultimate optimizations. From the Sublime Chord to the Master Spellthief feat, there are tons of things that you can pour into a build to get its CL through the stratosphere. So let's see how high this can really go. This thread is devoted to gaining the highest CL possible within 20 levels.

Here's the best I could think up:

Illumian Factotum 1 / Sorcerer 1 / Specialist Wizard 3 / Wu Jen 1 / Spellthief 1 / Bard 1 / Beguiler 1 / Warmage 1 / Hexblade 1 / Duskblade 1 / Magewright 1 / Sha'ir 1 / Savant 1 / Sublime Chord 1 / Knight of the Weave 1 / Hoardstealer 1 / Avenger 1 / Trapsmith 1

Its feats, in order, are Enhanced Sigils, Versatile Spellcaster and Heighten Spell (which allow entrance into Sublime Chord), Master Spellthief, Theurgic Specialist, and Reserves of Strength, plus 2 extra feats at higher levels.

(click to show/hide)

Sublime Chord has a CL for all arcane classes equal to her Sublime Chord CL (in this case, 1) and the CL of another class (in this case 3) combined. We add to this other factors that increase CL:

4 (Sublime Chord)
+ 3 (Enhanced Krau Sigil)
+ 1 (Ioun Stone)
+ 2 (Harmonic Chorus spell)
+ 2 (Hymn of Praise spell - thanks to the Sha'ir level, she is also a divine caster)
+ 2 (Rings of Arcane Might)
+ 1 (Adept Spirit)
+ 1 (Robe of Arcane Might)
+ 3 (Magic Tattoos)
+ 3 (Reserves of Strength)
+ 1 (Spellgifted Trait)

= 23

This means that her CL for all of those multitude of casting classes is 23. Next, we factor in Knight of the Weave, which adds the CL of every other arcane class to its own. 1 + 17*23 + 19 (for the bonuses listed above) = 411 CL for the Knight of the Weave.

Next, we look at Master Spellthief, which makes our CL for all of those classes the sum of the all of the classes' CL. Thus, every one of those 18 classes gains a CL of 411 + 17*23 = 832

Finally, we apply Theurgic Specialist, which allows us to add all of the classes' CL together when casting a spell of the specialized school. 832*18 = a CL of 14976.

Applying stacking appropriately, the best CL can be obtained by starting with Master Spellthief. This gives all of the 18 classes a CL equal to the sum of the class levels, or 20. To this, we can add the other factors that increase CL:

+ 3 (Enhanced Krau Sigil)
+ 1 (Ioun Stone)
+ 2 (Harmonic Chorus spell)
+ 2 (Hymn of Praise spell - thanks to the Sha'ir level, she is also a divine caster)
+ 2 (Rings of Arcane Might)
+ 1 (Adept Spirit)
+ 1 (Robe of Arcane Might)
+ 3 (Magic Tattoos)
+ 1 (Spellgifted Trait)
= 16 + 20 = 36

Next, we can apply Knight of the Weave, which gains a CL of 1 + 36*17 + 16 = 629

Finally, Theurgic Specialist adds all of those together for the purposes of casting, giving a final caster level of 36*17 + 629 + 3 (Reserves of Strength) = 1244

I found a number of spells that, even without the questionable implications of the Reserves of Strength feat, are uncapped and can be exploited by a caster with an incredibly high CL. I'll limit it, for now, to the 1st-6th level bard and wizard spells that a Sublime Chord could know, and I'll include a list in the next post.

[TheGeometer]

Reserved for the uncapped spell list

[sirpercival]

So, there are a few things I have for you. 

First, your calculations aren't correct.  You need to differentiate between boosts to your caster level for a particular class, and boosts to your caster level for arcane spells.  The latter category is tacked on at the end, and doesn't get double- (or ntuple-) counted.

Second, sublime chord gets 4th- thru 9th-level spells, not 1st thru 6th.

Third, Master Spellthief only adds your spellthief levels, not CL.

Fourth, both Master Spellthief and Theurgic Specialist sum everything up at the point of the spell, not the point of the class, so you don't get to double-count them either.

[TheGeometer]

So, there are a few things I have for you. 

First, your calculations aren't correct.  You need to differentiate between boosts to your caster level for a particular class, and boosts to your caster level for arcane spells.  The latter category is tacked on at the end, and doesn't get double- (or ntuple-) counted.

Second, sublime chord gets 4th- thru 9th-level spells, not 1st thru 6th.

Third, Master Spellthief only adds your spellthief levels, not CL.

Fourth, both Master Spellthief and Theurgic Specialist sum everything up at the point of the spell, not the point of the class, so you don't get to double-count them either.

Well, at the very least, I can say that your second point doesn't apply, because I only have 1 level of Sublime Chord which, plus the bonus from Spell Versatility and Heighten Spell, gives me 6th level spells maximum.

For your other observations, I suppose there are a number of problems. I had assumed that when both Master Spellthief and Theurgic Specialist influenced "your caster level for all arcane spells," it referenced overall caster level, so I failed to see that distinction. However, I do agree that some of the effects that I had added to the Sublime Chord CL reference the CL of each spell, and must therefore be added at the end.

If someone could help with the calculations, it would be much appreciated. The goal, after all, is for the highest legal 20th level CL, so I need to know what the actual CL of the build I just created is, given stacking rules. From there, we can try to improve it.

[sirpercival]

The distinction is "your CL for all arcane spells" vs "your CL for X class". 

I'll do the math for you, but not right now... I don't have time.

[TheGeometer]

I did the math, and found that without the stacking errors, the build's CL falls to a (relatively) mere 1244. I'm pretty disappointed with that, since it's less than a tenth of the first value I got. Does anybody know any methods of boosting CL that I missed?

[sirpercival]

Well, since this is YBIYBI I can make some broken suggestions.

The classic one is stacking Greater Consumptive Fields ad nauseum.  However, I have a more fun way.  It only lasts for 48 hours, but it's nice nonetheless (and if you happen to be using a particular homebrew variation on epic magic you can make it permanent).

Needed:
~Reserves of Strength feat
~Elven Spell Lore feat
~Sanctum Spell feat
~Persistent Spell feat
~Lesser Extend rod
~Shadowcraft Mage (wizard)/Incantatrix 3 with the ability to cast Shadow Miracles out of a 6th-level slot (via Easy Metamagic Heighten, Sanctum, Arcane Thesis, Invisible Spell, etc.)
~Signature Spell: Silent Image
~Knowledge of the following spells: Shapechange, Manyjaws, Suffer the Flesh, Arcane Fusion, Arcane Spellsurge, any 6th-level spell
~Command-word item of Mage's Lucubration

Begin by persisting Shapechange and Arcane Spellsurge using Metamagic Effect.  Cast a 6th-level spell, Sanctum-down to 5th-level.  Then shapechange into a shambling mound.

• Each round, cast Arcane Fusion as a swift action using a 6th-level Shadow Miracle.
• The two spells you will be duplicating are a Sanctum-down, Reserves of Strength Suffer the Flesh for max Con damage, and a Reserves of Strength Manyjaws with the damage changed to electricity via Elven Spell Lore.
• With your standard action, trigger your command word item to regenerate the 6th-level spell slot.

Doing this for N rounds will increase your CL by a factor of 1.5^N, and you can have it last for 48 hours by Persisting the final Suffer the Flesh and using the Extend rod to double the duration.  So, if you do this for 24 hours minus say a minute of prep time (the length of your persisted shapechange and arcane spellsurge), starting with a CL of 20, your final CL will be 20 * 1.5^14390, or approximately 1.8e2535.

The advantage this has over stacked GCFs is that you don't need to kill anyone to do it.

Now, this is a very feat-intensive solution, so I suggest starting as an Elf and using DCFS on your racial proficiencies.

[awaken_D_M_golem]

Bauglir has the CL Loop guide, same general idea(s).
http://brilliantgameologists.com/boards/index.php?topic=9983.0

[TheGeometer]

Bauglir has the CL Loop guide, same general idea(s).
http://brilliantgameologists.com/boards/index.php?topic=9983.0

I've read it before. CL optimization has obviously been done before, but I couldn't find anything in the handbook that indicates a record highest legal CL.

As for Sirpercival's method, all I have to say is, shambling mound strikes again. I think every shambling mound gimmick I see impresses me more than the last. Bravo.

[awaken_D_M_golem]

It's all good.

... The classic one is stacking Greater Consumptive Fields ad nauseum ...

The psi version is Chaos Fissure 8 in CPsi over and over.
Needs the powerpoints to do it, or an item.

[sirpercival]

By the way, if you also extend the Shapechange and Spellsurge with a rod, you get 48 hours - 1 minute of boosting... so you'd have a CL of 20 * 1.5^28790, or roughly 9.3e5070.  That's probably the record.

[Bauglir]

I've been doing some thought on Consumptive Field. Assuming you have access to a bag of infinite rats or a similar mechanism to gain the highest possible bonus as soon as you cast the spell, there's a couple results worth noting.

The spell is the same effect in different strengths - the bonuses don't stack. As a result, the boost you can gain halves with each casting. This is still a significant boost - a CL 20 caster winds up with CL 38, the maximum bonus, after 4 castings (CL 30, 35, 37, 38). A vague recollection of calculus suggests that you approximately double your caster level, with rounding errors.  (EDIT: Pure intuition suggests that the error is always -2 for an even starting CL. Not sure about odd ones, and could very easily be wrong about this hypothesis)

Additionally, boosts from Consumptive Field can't boost that spell's duration, so no matter how high it boosts your CL, it only lasts for as many rounds as your CL was when you started. Persistent Spell may be able to alter this, I don't know.

Suffer the Flesh has similar problems, in addition to a hard cap of +5 CL. It's worth noting that while it is an increase and not a bonus, the spells are what don't stack (not the alteration to your CL). Forgot about RoS. I interpret the feat differently, but in that I differ from the common reading. It's not overpowered for it to entirely break the cap on CL on spells in the contexts for which it was intended, either (blasting spells).

[sirpercival]

By the way, if you then do an RoS Manyjaws, that breaks the record for non-infinite individual attacks.  And probably non-infinite damage.  You can also get the highest skill checks with an RoS Divine Insight, the highest AC with an RoS Magic Vestment, etc.

[Cyclone Joker]

As previously posted, sirpercival's build doesn't work for about a half-dozen reasons, most notably that Shadow Miracle doesn't work. Also, Metamagic IN an Arcacane Fusion doesn't work. By very strict RAW, this also raises the issue that none of your spells are, strictly speaking, sorcerer spells, and so don't actually work with Arcane Fusion, though this one is slightly more arguable.