Arcane Fusion Loop

[The Insaniac]

I was looking at arcane fusion and sanctum spell and an exploit occurred to me. Is it possible for me to cast arcane fusion and then use rapid metamagic and the free fourth level spell that I get to cast a sanctum arcane fusion? As far as I can tell, I can do it because sanctum spell says "...if not cast in the sanctum, the spell has an effective spell level 1 lower than normal. All effects dependent on spell level (including save DCs) are calculated according to the adjusted level." However, a sanctum spell still uses a spell slot of the same level as the base spell which might keep that from working.

And yes, I know that this is exploitative if it works, but this is a TO question not a PO question.

[Karnith]

The (Greater) Arcane Fusion loop is an old trick.

I know of two points of contention about whether or not it works. The first is whether or not Arcane Fusion's spell level requirement is an effect. Since to the best of my knowledge WotC never defined "effect," or in this case how far-reaching "effective spell level" is, it's difficult to point to something that validates (or invalidates, for that matter) Sanctum'd Arcane Fusions. The second is that Sanctum Spell doesn't modify the spell's effective level until the Sanctum'd spell is cast, meaning that the Sanctum'd spell wouldn't be eligible to select with Arcane Fusion because it hasn't been cast yet (and hence its effective level hasn't been lowered yet).

EDIT: Oh yeah, and the errata kind of nixed the trick unless you believe that effective spell level somehow applies to/overrides the limits put in by the errata:

Page 96 – Arcane Fusion [Addition]
Include clause, “If applying a metamagic feat to a spell, use the adjusted spell level and casting time for purposes of determining eligibility for Arcane Fusion.”

[Darrin]

Hmmm. Earliest I can find is a post from RigaMortus2 on ENWorld in 2007.

http://www.enworld.org/forum/showthread.php?194907-How-Many-Spells-Can-You-Cast-In-A-Round/page2

I'm not sure if he discovered it first. But yeah, old trick.

[Urpriest]

The (Greater) Arcane Fusion loop is an old trick.

I know of two points of contention about whether or not it works. The first is whether or not Arcane Fusion's spell level requirement is an effect. Since to the best of my knowledge WotC never defined "effect," or in this case how far-reaching "effective spell level" is, it's difficult to point to something that validates (or invalidates, for that matter) Sanctum'd Arcane Fusions. The second is that Sanctum Spell doesn't modify the spell's effective level until the Sanctum'd spell is cast, meaning that the Sanctum'd spell wouldn't be eligible to select with Arcane Fusion because it hasn't been cast yet (and hence its effective level hasn't been lowered yet).

EDIT: Oh yeah, and the errata kind of nixed the trick unless you believe that effective spell level somehow applies to/overrides the limits put in by the errata:

That errata looks like it explicitly allows the trick, not nixes it. The adjusted spell level is presumably the level the feat adjusts the spell to, after all.

[Karnith]

That errata looks like it explicitly allows the trick, not nixes it. The adjusted spell level is presumably the level the feat adjusts the spell to, after all.
I thought the metamagic feat rules used the term "adjusted spell level," but they don't so far as I can tell. :smallsigh: My mistake.
Naturally, of course; otherwise the erratum might have fixed something!
On a RAI basis, a spell modified by Sanctum Spell uses a spell slot of the spell's normal level, which is clearly the adjusted spell level that the errata is referring to; otherwise, only Heighten Spell and Sanctum Spell have adjusted spell levels, and Earth Spell would screw with your Arcane Fusions. Using the RAW of the Complete Mage errata, though, a(n Arcane Thesis'd) Twinned Split Maximized Enervation would still be eligible for Arcane Fusion (provided that you get the casting time down), as most metamagic feats don't adjust spell levels.

Even bearing that in mind (i.e. back to RAW), though, you still run into the issue of Sanctum Spell not modifying a spell's effective level until you actually cast the spell (i.e. too late in the process for it to be eligible for Arcane Fusion).

[The Insaniac]

Okay, but the wording for arcane fusion is "Both spells take effect... as if you had cast them one after the other... Effectively, you cast two other spells using this spell's 5th-level spell slot." Which means that you never actually cast the spells, the effects simply appear as if you had cast them. So the final levels of the spells would need to be within the parameters of arcane fusion but because the effects simply occur, you might not need to have the unmodified spells be workable. This is, of course, purely a matter of interpretation of the spell's wording.

Edit: Yeah, I didn't think I was the first one to find this.