Succubi Ultimate Magus

[Saambell]

This is mostly just theory, and personal interest. Probably won't run in an actual game. I saw the Ultimate Magus PrC, then found a Succubus Monster PC Class that subsitutes for race and a class. http://www.giantitp.com/forums/showpost.php?p=7951939&postcount=29. I started to wonder how to combine them.

This is mostly just for the sake of having a Succubus Spell Caster.

For the UM.

ENTRY REQUIREMENTS
Skills: Knowledge (arcana) 4 ranks, Spellcraft 8 ranks.
Feats: Any metamagic feat.
Spellcasting: Able to spontaneously cast 1st-level arcane
spells, able to prepare and cast 2nd-level arcane spells
from a spellbook.
Now a major problem is how the +1 levels apply. The Succubi page says that for it the difference is what they actually gain. So a Succubus 1 adds a Sorcerer level. Giving 1 Cantrip and 1 1st spell slot, but only 1 cantrip known So the first stumbling block is; For the prerequisite to Spontaneous cast a 1st lvl spell do I have to know one too? Or is it just looking for slots?
Also since I would need both INT and CHA normally is there a Prepared Arcane Caster who uses CHA as the Spell Attribute?

In the Level Progression path it would go something like this maybe:
L
1 1Suc
2 2Suc
3 1Sor
4 1Wiz
5 1UM adding Level to Sor to tie up the Spell Levels
...And from there? Build along Ultimate Magus? Or from there jump to another PrC? At some point I would like to get 2 more levels in Succubus for the wings ability. and the additional 2 CHA is nice.

Also the Spells Known/Spell Slots are just headache inducing. Because you are looking at the new effective level compared to the previous level and adding the difference of the two, where applicable, to your actual list of spell slots/spells known.

Or would a Mystic Thurge be a wiser choice? Using Sorcerer and with the bonus of Clerics having their WIS Swapped for CHA. though they lose out on domains. or is there an actual CHA based Divine caster that would be better?

Any advice would be welcome. Again this is just personal interest. I doubt I will ever play it. I sort of collect Unused Characters. I spent several years with the PHB and no one to play with, so I amused myself by making characters.

[sideswipe]

firstly, even if it works the way you want it to, in your build you cannot prepare a second level spell from a spellbook. you have 1 level of wizard, meaning you can only prepare and cast first level spells from your spell book. it is specific,

you cannot take precocious apprentice as that is a 1st level only feat.

so you would need 3 levels in wizard.

[Saambell]

Check again. as far as i can tell the 2 levels in the Succubus class also boost the levels of the wizard class. i would be only able to cast 1 2nd level spell and nothing else. I would be a level 3 wizard, but only get the difference between 2nd and 3rd level wizards in spells.

[Urpriest]

The monster classes are occasionally kind of weirdly designed. In this case, I doubt that the intent was for it to add to multiple casting classes at once (though it might have been, given that that's how it works in ToB).

There aren't any Cha-based spellbook classes, so Cleric would indeed be less MAD, as would substituting Beguiler for the Sorceror.

You should be able to actually cast a 1st level spell spontaneously, so you'd need some way to access that. Heighten might suffice.