I'm making a Beguiler 1/Wizard 4/Ultimate Magus X. Using the practiced spellcaster feat, I can make sure that levels 1 and 4 of UM count towards my wizard class. However, at level 7 of UM, the increase in class spells would need to be used on the beguiler class. So, instead of going Beguiler 1/Wizard 4/Ultimate Magus 7, I'm thinking of going Beguiler 1/Wizard 4/Ultimate Magus 6/Beguiler +1. That way, when I take Ultimate Magus 7, I can apply it to my wizard side.
My question is, if I do that, does that mean I would be increasing my Beguiler class level to 2 (gaining cloaked casting and surprise casting), but would be gaining the spells equivalent to Beguiler 6?
In-depth description of how Practiced Spellcaster and ultimate magus interact
Since there seems to be some confusion on this point:
Practiced Spellcaster “tricks” ultimate magus into advancing the class you don’t take it in, even if that class would otherwise have more advanced spellcasting.
Normally, ultimate magus advances the class with the lower level at 1st, 4th, and 7th. But “lower level” is defined by caster level, rather than your effective level in that class for spellcasting, which means that even though you are a Beguiler 1/Wizard 3, your beguiler caster level is 4th, higher than wizard’s 3rd, when you choose to take your first level of ultimate magus. Therefore, it advances your wizard spellcasting, even though wizard spellcasting is mostly more advanced.
This means Practiced Spellcaster does affect maximum spell level, spells per day, and spells known for an ultimate magus.
After taking that level of ultimate magus, which advances wizard spellcasting but not beguiler spellcasting (but grants a +1 caster level bonus to both), your caster level for beguiler is 6th (1 class level, +4 from Practiced Spellcaster, +1 from Arcane Spell Power), and your caster level for wizard is also 6th (3 class levels, +1 from ultimate magus level, +1 from Arcane Spell Power). They remain even until Ultimate Magus 4, at which point (because the caster levels are even) you get to choose. You choose wizard, so it pulls ahead.
So by the time we we go to apply the 7th level of ultimate magus, we have the spellcasting of a 9th-level wizard at caster level 11th, and the spellcasting of a 7th-level beguiler at caster level 10th. Therefore, ultimate magus would “pick” beguiler for us.
The question is, since ultimate magus would “pick” beguiler anyway, is it better to take another level of beguiler at this point, getting its class features, and then ultimate magus can advance wizard spellcasting instead?
And if I do this, which beguiler class features do I get, those of Beguiler 2 but with the spellcasting of Beguiler 6?