CL = X + any other arcane caster levels loop

[Smegskull]

So I have a loop I need to figure out what to do with.
class A has an arcane caster level = 2 + half level + caster level from another arcane class
class B has an arcane caster level = class level + any other arcane caster levels you may have....

so A level 5 and B level 2
A = 2+2+B, B = 2+A So A = 2+2+2+A[2+2+2+A[2+2+2+A[2+2+2+A[2+2+2+A[...]]]] etc?

[mattie_p]

Without knowing the specifics it's hard to calculate the interactions. What classes, what feats, is this 3.5 or PF, etc?

Edit: I'm guessing Spellthief with MS and maybe Unseen Seer? That's come up before.

[Anthrowhale]

Is it arcane caster level? Or arcane class level?

[Smegskull]

Is it arcane caster level? Or arcane class level?
"Knights of the Weave cast arcane spells like a sorcerer (you use your Charisma score to determine bonus spells per day, save DCs, and so on). Refer to Table 4—3 to determine your spells known and spells per day. You incur the normal arcane spell failure chance for wearing armor (but see Armored Caster, below). Your caster level for your knight spells is equal to your knight class level plus any other arcane caster levels you may have."

[Calthropstu]

"Knights of the Weave cast arcane spells like a sorcerer (you use your Charisma score to determine bonus spells per day, save DCs, and so on). Refer to Table 4—3 to determine your spells known and spells per day. You incur the normal arcane spell failure chance for wearing armor (but see Armored Caster, below). Your caster level for your knight spells is equal to your knight class level plus any other arcane caster levels you may have."

Oof. Yup, MS plus that really breaks stuff. But it isn't infinite. Unless BOTH say caster level stacks. In which case...

Personally, I'd use order of operations. Whichever class came first is added, then the later class is added. Stop it there.

[mattie_p]

I'm looking at the general rules for stacking modifiers, it only talks about modifiers to dice rolls however.
In most cases, modifiers to a given check or roll stack (combine for a cumulative effect) if they come from different sources and have different types (or no type at all), but do not stack if they have the same type or come from the same source (such as the same spell cast twice in succession). If the modifiers to a particular roll do not stack, only the best bonus and worst penalty applies.

So doesn't quite address the situation, which is too bad as it would have neatly cut the knot. As DM that's probably where I would land though, unless I find a better rule.

What's the other class involved, Spellthief + Master +something else?

[Beni-Kujaku]

I don't know what the RAW would be. But if you are asking what would make the most amount of sense and still be usable in a normal game, I'd say just disregard the loop. Calculate the caster level of each of your classes independantly, and only then use the feat. So, in the case of a wizard 5/Spellthief 4/KotW 3/Nar Demonbinder 5, the caster level of the Knight alone would be 3+4+5+5=17, and the one from Nar demonbinder would be 5+5=10 (you don't add the increased CL from the knight). Then the feat comes into play and you have a CL of 5+4+17+10=36 for all classes.

[Darg]

Mystic Fire Knight paladin sub levels is probably the other class:


Improved Spellcasting (Ex): When casting paladin spells, a Mystic Fire Knight can treat her caster level as equal to one-half her paladin level +2. If she also has arcane spellcasting ability from another class, she can add her caster level from that class to this value to determine her paladin caster level.

Using a single level of an arcane caster such as a wizard for the Sword of the Arcane Order feat would start the infinite loop.

Of course, this combo hinges on SotAO feat granting arcane caster status to the paladin. Is the ability to cast spells of a different source granting dual source casting status similar to the Sha'ir class? Southern magician doesn't do this because it is still a divine spell, just changing the source of that spell when you cast it.

Personally I would say yes, but limit the order of application of CLs in the most favorable way while not allowing an infinite loop. SotAO does grant the ability to cast arcane spells (but not the knowledge of them).