(http://www.worldofazolin.com/wiki/images/thumb/c/c6/Ultimatemagus.jpg/180px-Ultimatemagus.jpg)
Race: Human (any) or Elf (any)
Class: Divine (Domain) Dragonblood Planar Sorcerer 6 (or whatever grab bag of ACFs you like) / Knight of the Weave 1 / (Spontaneous Variant) Ultimate Magus 1 / Spellthief 1 / Ultimate Magus +9 / Any 2
Feats:
Magical Training (wizard)
Versatile Spellcaster
Master Spellthief
Reserves of Strength (if you read it the removes cap way)
Arcane Preparation and/or Heighten Spell (if you're not allowed to use the spontaneous variant of Ultimate Magus)
Skills: Craft ((basket)weaving) X, Max Spellcraft & Concentration, Knowledge (arcana) 4, Knowledge (history) 1
Spells: Wings of Flurry, Holy Word/variants (via spellpact, Ring of Theurgy + Planar Binding, sorcerer's domain ACF, playing sorcerer the way it was meant to be per Dragon Magazine #338 p97, etc.), other spells that don't have a cap or who are horrendusly broken when their cap is removed
Items: Tome of Ancient Lore 5,500gp (because why not know every arcane spell on the sorcerer/wizard list--more on this later), Ring of Arcane Might 20,000gp and Orange Ioun Stone 30,000gp (lets our CL even more ridiculous), etc.
Hook: "I am the ultimate Meh-gus."
Build Breakdown:
Caster level:
This is the bread and butter of what the build does. It exploits the lack of rules on the subject of increasing caster level other than applying them in the most beneficial/favorable way. The main trick is piling three separate abilities that calculate their caster level based on other caster levels, two of which can theoretically be adjusted more than once and one of which binds them all together, for a strictly increasing "final" caster level total. These feats/features are: Knight of the Weave's spellcasting class feature, the Magical Training feat, and the Master Spellthief feat.
Here's what the rules have to say about them:
"Thereafter, you [...] are treated as a sorcerer or wizard of your arcane spellcaster level (minimum 1st) for the purpose of determining level-based variables of the spells you cast."
- Magical Training (FRCS p41)
"Your spellthief and arcane spellcaster levels also stack when determining your caster level for all arcane spells."
- Master Spellthief (CS p79)
"Your caster level for your knight spells is equal to your knight class level plus any other arcane caster levels you may have."
- Knight of the Weave (CoV p111)
Both Magical Training and Knight of the Weave operate in a way that implies their caster level is capable of changing depending on adjustments to other caster levels. This means there is potentially a TO argument for them being adjusted more than once. Essentially, the argument is: because your Knight of the Weave caster level and wizard caster level from Magical Training are constantly going up in response to one another, you could "theoretically" go infinite for their respective CLs. Adding infinity to your other caster levels with Master Spellthief is what would make your overall caster level infinite.
Using the above order of operations, the base calculation for the respective caster levels involved in the build would look something like this (without Arcane Spell Power):
18 (sorcerer) + 8+K (knight) + W (wizard) = M (master spellthief)
where K = other arcane caster levels (than Knight class-based CLs)
where W = arcane spellcaster level
where M = Spellthief levels + arcane spellcaster levels
The problem with this is determining K, W, and M as K and W go up in response to any other increase, and would even technically go up again after the Master Spellthief caster level is calculated (although would obviously not be capable of affecting the Master Spellthief calculation more than once). This would give us three seperate caster levels.
To resolve this, we can have the Knight of the Weave class add the wizard CL only once and have the wizard CL calculate itself only off of our sorcerer CL and never have either readjust themselves:
18 (sorcerer) + 18 (wizard) + 8+36 (knight) = 80+1 (master spellthief) + 4 (arcane spell power) = CL85
Of course, the problem with this calculation is that our Knight and wizard CL still don't include our "Spellthief" CL in their final calculation, but I still think it works fine by certain readings of the respective feats and class abilities to consider Master Spellthief as the final piece of glue for a single unified CL.
The spellbook:
Magical training gives us a spellbook with 3 0th level spells in it and we:
"are treated as a sorcerer or wizard of your arcane spellcaster level"
"have a spellbook"
"prepare your spells exactly as a wizard does"
- Magical Training (FRCS p41)
Based on rules compendium:
"Spellcasters who use spellbooks can add new spells to their spellbooks through several methods."
- Adding Spells to a Spellbook (RC p160)
The feat Magical Training quite clearly treats us as a spellcaster who uses a spellbook for the purpose of our 3 0th level spells known (as a wizard who casts spells from the sorcerer/wizard list to be exact). Fortunately for us, wizards can add spells above the level they're able to cast to their spellbooks, so long as they can make the required spellcraft check. Of course, we don't have any wizard spell slots (other than 0th level) from which to cast the spells we've added to our spellbook. That's where Versatile Spellcaster (or Arcane Preparation) comes into play:
"You can use two spell slots of the same level to cast a spell you know that is one level higher."
- Versatile Spellcaster (RotD p101)
Because we know the spells in our spellbook on the wizard side (refer to the Arcane Spells section of the SRD for the reason why, because I'm growing lazy), we cast them freely by expending two lower level slots and have a combined caster level to meet any caster level requirements the spells may have.
Versatile Spellcaster:
We had a 2 level setback to our sorcerer spellcasting progression due to our Spellthief and Knight of the Weave dips, but that doesn't mean we need to fall behind with the highest level of spell we're able to cast. Versatile Spellcaster coupled with our spellbook keeps us on track with a regular sorcerer 20, solving the common sorcerer multiclass problem.
A few questions to consider:
Does Versatile Spellcaster let you get around the 1/day limitation of the Domain spells ACF?
Why not? This is the "famous optimized character builds" thread where everything should be read in the most favorable manner possible.
Why did you use Ultimate Magus if the class's main shtick doesn't even require it?
Because for some reason people love that class (even though it can't stack metamagic with its keynote feature). Also for the name. And if we're being honest, it does give you a significant CL boost even if you don't apply the caster levels infinitely.
I'll add more as they come up and as I have more time.