What's the highest possible Charisma score you can end up with in Pathfinder, using official Paizo material only, assuming that you have an equivalent wealth level of a level 20 character?
Unlikely to be the highest possible, but the highest typical 20th-level ability score, assuming you’re focusing on it, is 36:
- 18 base
- +2 racial
- +5 from levels
- +6 from enhancement bonuses
- +5 from wish or a manual
For mental scores, there is also the +3 bonus you can receive for being venerable. These usually come with a −6 penalty to all physical scores, so this is not generally considered optimal unless you have some way of ignoring the penalties (losing 60 HP and taking a −3 to initiative isn’t worth +1 to your DC, even if you have no other uses for physical scores). But you could get to 39 by being venerable.
Anything beyond this requires special bonuses that are not typically available: unusual items that grant non-enhancement bonuses to an ability score, feats or class features that improve an ability score, and so on. Strength and Constitution get a lot of these, and Dexterity some, but mental ability scores only receive such bonuses rarely. I am not aware of any for Charisma, though I don’t doubt there are some.
So, this answer attempts to put forth the highest possible score, given the limitations in the question. I will also make additional assumptions as necessary, generally in order to eliminate a situation where the answer would be 'arbitrarily high' due to your failure to account for one kind of resource or another in the phrasing of the question. I'll try to be clear about each assumption as I decide to make it. To start off, obviously it is to our advantage to possess more gold, so we will take the assumption that the campaign is high fantasy, and thus the expected wealth of a 20th level character is 1,760,000 gp.
A character's total Charisma score is a composite entity, the result of myriad sources combining additively or not at all.
Like all ability scores, a character's total Charisma is the result of a base value modified by various bonuses and penalties. Bonuses and penalties function identically in pathfinder with regards to Charisma and it is sufficient to think of a penalty as a negative bonus. Therefore, since the possible bonuses and the possible base values are not correlated, we have simply to divine the maximal bonus and the maximal base value and additively combine them.
For the purposes of this answer, let us treat 'untyped' as a bonus type. Then we can say that every bonus has a type, and that the application of a specific Charisma source to the total Charisma score is always governed only by the union of rules specific to that bonus type and those applicable to bonuses in general. If no bonus type depended upon any other type to determine its effect, we could look at each kind of bonus individually. Unfortunately, because the maximal bonus of a given type may be weakly linked to that of another type by the existence of magic item slot limitations, this may not be ultimately successful. However, we will take the assumption that individual maximal charisma bonuses are fully independent for ease of presentation and then resolve any inconsistencies later.
Maximal Base Value
The maximal base value for an ability score at level 1 is 18, regardless of chosen official chargen method.
All of the methods described above allow for a maximum score of 18. The minimum ability score possible when using an official method varies between 3 (for Standard and Classic) and 8 (for Heroic). (source)
Ability score increases at levels 4, 8, 12, 16, and 20 can raise this base value to 23.
Mythic ability score increases at tiers 2, 4, 6, 8, and 10 can raise this value to 33.
The 6th level spell Flesh to Stone allows us to become mindless which, in combination with the 3rd level ranger spell Instant Enemy cast by a character with the favored enemy class feature and the 'construct' favored enemy type, lets us qualify as a valid target for the 5th level spell Awaken Construct. Awaken Construct instantaneously increases our base Charisma score by 2d6, and a Maximized Double Empowered Awaken Construct instead can increase our base score by as much as 27 (12 base, plus 6 from the first, feat-based, empowerment and 9 from the second, metamagic-gem-based, one). Although Awaken Construct, like all Awaken-type spells, self-stacks infinitely, we will assume each can only be used once instead. This brings our base Charisma score to 60.
The Awaken spell itself can be used similarly, and grants 1d3 (3+1+2 at most when double empowered) Charisma, which brings the grand total for our base Charisma score to 66.
Our maximal base Charisma score is thus 66.
Bonuses by type (or lack thereof)
An alchemist can gain access to Cognatogen and with the Grand Mutagen discovery as well, this allows a Cognatogen that grants a +8 bonus to Charisma. While non-alchemists cannot drink mutagen, even a single level of alchemist allows us to benefit from the full effects of such a power, and a UMD check to emulate a class level may well work instead. The maximal alchemical bonus is thus +8.
Armor bonuses do not apply to Charisma. The maximal armor bonus to Charisma is 0.
BAB has tons of special rules governing its value and application, and extra definitely does not ever apply to Charisma. The maximum here is 0.
Circumstance bonuses self-stack as long as they are from different sources. Unfortunately, while there are many, many ways to gain a circumstance bonus to particular uses of Charisma, there are none to gain a circumstance bonus to the ability score itself; the maximal bonus is 0.
nothing for Cha. Maximum value 0.
Often equal to Charisma, but never applied to it. Maximum is 0.
Another self-stacking bonus that never applies to Charisma. Maximum is 0
The maximum Enhancement Bonus to Charisma is, unfortunately, infinite, as the resonant power of a regular or flawed pink and green sphere ioun stone can self-stack infinitely with infinitesimal probability. We take the assumption that rolls of 91-93 on the resonant powers table affect the cost of an ioun stone such that its total price is multiplied by the number of effective resonant powers it has. With a full investment of half our gold, this can result in a +294 enhancement bonus to Charisma at the cost of a -2 penalty to Constitution. If the 'Advanced Ioun Stones' section is instead used so as to avoid having to fiddle with arbitrarily marking-up the prices of certain resonant power combinations, and we limit ourselves to a single +2 from the resonant power, the value sharply decreases to a mere +22 enhancement bonus to Charisma. Including the probable 50% cost modifier for a scorched stone, we would get a +31 enhancement bonus instead. We will use this third, lowest value in our total calculation as it involves the least arbitration on our part without being flatly infinite.
Custom Magic Item Creation can just barely beat this-- a custom item granting an enhancement bonus to charisma can reach +29 for half our WBL.
Ultimate Campaign allows us to exceed WBL by 50% by taking crafting feats, which is a good trade since feats can't get us Charisma. This raises the totals to infinity, +440, +27, and +38 for ioun stones, depending on what method we used to calculate things, as above, or +36 for the Custom Magic Item method.
The maximal Inherent Bonus is +5, which can be most cheaply acquired through castings of Wish in which the material components are provided by chain-casting Fabricate on cheap diamonds in order to avoid the gp cost of the process. This allows us to get this bonus without it consuming more than a trivial amount of our WBL.
Nothing applicable, maximum 0.
Nothing applicable, maximum 0.
There's some 3pp stuff, but nothing Paizo. Maximum 0.
The Profane Ascension ability of the demon lord Nocticula grants a +6 profane bonus to charisma. Maximal bonus is +6.
The highest racial bonus accessible through published material can be gained through the 'Creating New Races' rules-- theoretically, such improvement is potentially infinite. We make the assumption that the race so created must spend no more points than would be allowed without level adjustment for a 20th level character. This limits us to 40 RP. The ideal race for strictly maximizing Charisma is as follows:
Type: Outsider(native) (3)
Size: Medium (0)
Base Speed: Slow Speed (-1)
Ability: Paragon (+4 Charisma) (1)
Language: Standard (0)
Weaknesses: Elemental Vulnerability (acid,cold,electricity,fire) (-8), Vulnerable to Sunlight (-2), Light Blindness (-2), Light Sensitivity (-1), Negative Energy Affinity (-1)
Ability Score Racial Traits: Advanced Charisma X 7 (49)
Which leaves 1 RP free for either not taking a 1 point weakness or buying something else.
This leads to a maximal racial bonus of +18
No dice. Max is 0.
Luthier's Rapier costs 5,020 gp and grants (among other things) a +4 sacred bonus to Charisma 1/day. This appears to be the only source of a sacred bonus to Charisma.
Genious Avaricious, when choosing the 'Mammon's Mantle' option, can grant a +5 untyped bonus to Charisma.
The madness of the Derro appears to grant a +6 Charisma bonus and a -6 Wisdom penalty. If this is not the case then repeated affliction with the madness and curing thereof would allow arbitrary wisdom gain at the cost of arbitrary Charisma loss. Since we make the assumptions needed to prevent infinite stats, we will allow that this provides such a +6 untyped bonus.
Being Venerable gives a +3 untyped bonus to all mental abilities
Having the Contaminated Personality manifestation of the Possessed corruption grants you a +2 bonus to Charisma so long as the possessing spirit has at least 4 points of influence over you.
The Enhanced Ability 3rd-tier universal path ability can grant a +2 bonus to Charisma.
Final Summary and Total
We haven't come close to exceeding any slot limitations or spending all our gold or anything like that so there aren't any corrections that need to be made here since it turned out that the maximal bonus in each area was independent. Yay!
Via the methods outlined above, our estimate for the highest possible charisma score for a player with unlimited access to Paizo material but no 3pp material at level 20 and neglecting the possibility for infinite attributes is 18 base +5 from levels + 10 from mythic tiers + 33 from awaken-like things + 8 alchemical + 36 enhancement + 5 inherent + 6 profane +18 racial +4 sacred +5 untyped from greedy evilness +6 untyped from insanity +4 untyped from being a ghost +3 untyped from being really old +2 untyped from mythic path abilities +2 untyped from being possessed by an evil spirit= 165 Charisma.
You can also get 144 without being a possessed, lust-crazed, demon-worshipping, insane undead abomination, if you're into that sort of thing.