Question: How to calculate CL for Ultimage Magus KotW?

[Redeemer of Ogar]

OK, it's simple math one way or the other, but I'm looking for a RAW source for which way to fall:

Knight of the Weave caster level is "equal to your Knight class level plus any other arcane caster levels you may have."
Arcane Spell Power (from UM): "At 1st level, your caster level for all arcane spells increases by 1. It increases again at 4t level..."

Assume the progression Wizard 5/Knight of the Weave 1/Ultimate Magus 5.  (Knight entered through Spontaneous Divination).

Wizard is always your lowest CL, so UM always advances Wizard. Therefore, your wizard CL is 5, plus 5 for UM levels, plus 2 for Arcane Spell Power, for a total Wizard CL of 12 (and an effective Wizard Level of 10 for spell slots).

Knight of the Weave does not advance at UM1 or UM4, so your KotW effective level is 4. Your KotW class level is still 1 of course.  And here is where the confusion comes in... what is your KotW Caster Level?

Is it 13 (your Wizard CL plus your KotW class level)?
Is it 13 (your Wizard effective level, plus your KotW class level, plus Arcane Spell Power)?
Is it 15 (your Wizard CL, plus your KotW class level, plus Arcane Spell Power)?

...or something else?  I had thought it was option 1 above, but a random question made me start to question it.

[Emy]

Just from a glance, I think it's the second option.

[Rebel7284]

I think this is an area of the rules that was never fully defined.  Thus you're unlikely to get a consensus.

Edit: with that said, option two does indeed seem to make the most sense.

[Redeemer of Ogar]

OK cool.  That's actually what I'd been using, as getting double-bonus from CL-boosting feats and spells seemed a bit cheesy.  I was just curious if I was deliberately gimping myself to avoid cheese, or accidentally using the right calculation. 

[woodenbandman]

It says "your class level plus any other arcane caster levels you may have." That means that you add the advances from UM, the advances to wizard, and Spell Power. I'm guessing that it's option C, or 15.

I can't wait to add Sublime Chord to this.

[PhaedrusXY]

It says "your class level plus any other arcane caster levels you may have." That means that you add the advances from UM, the advances to wizard, and Spell Power. I'm guessing that it's option C, or 15.

I can't wait to add Sublime Chord to this.

"To infinity, and beyond!"