Arcane Fusion infinity

[Max Caysey]

I know this is an old one, and I have found different answers to this on various forums. I would like to know once and for all whether or not it can actually be done. The infamous infinity loop wit the sanctum spell.

As I understand it it can only be done by some very advantageous RAW readin. Is it possible for this community, to explain how, if indeed possible of specifically the text that makes it so.

Also I was under the impression that Arcane Thesis made it possible to actually reduce the level of the spell below the original level, but this seem untrue...

Also, how if possible would this be done with a wizard?

I need some help. Thanks.

[OldTrees1]

The Sanctum Spell metamagic feat is a +0 metamagic feat that increases/reduces the effective spell level by 1 when you are inside/outside of your sanctum.

[Fouredged Sword]

When using sanctum spell arcane fusion you cast arcane fusion as a 4th level spell. You cast it out of a 5th level spell slot, but it is a 4th level spell for all effects, including the ability to be cast using arcane fusion.

[Chronos]

And yes, this is a really stupid rule, and you'd be perfectly justified in houseruling it away. But you should always know what's broken about something before you set about fixing it, and acknowledging that the problem exists is the first step.

[Fouredged Sword]

Yeah, sanctum spell should specify that you count the spell as 1 level higher in your sanctum "When it is benifical for you to do so" and count as one level lower outside your sanctum "When doing so would be detrimental".

Ether that or specify it is simply +1/-1 to save DC and counts as one level higher/lower when interacting with effects that block or absorb spells.

[Extra Anchovies]

Yeah, sanctum spell should specify that you count the spell as 1 level higher in your sanctum "When it is benifical for you to do so" and count as one level lower outside your sanctum "When doing so would be detrimental".

Ether that or specify it is simply +1/-1 to save DC and counts as one level higher/lower when interacting with effects that block or absorb spells.

Actually, Sanctum Spell probably shouldn't exist, period. I know of exactly zero builds that use it for its intended purpose, because how often are adventurers in one place anyways?

[Thrice Dead Cat]

Actually, Sanctum Spell probably shouldn't exist, period. I know of exactly zero builds that use it for its intended purpose, because how often are adventurers in one place anyways?

To be fair, its "intended" purposes may very well be to get into prestige classes early or to allow the application of higher level spells to various things (e.g., arcane fusion, metamagic rods, war weaver's abilities).

[ahenobarbi]

Actually, Sanctum Spell probably shouldn't exist, period. I know of exactly zero builds that use it for its intended purpose, because how often are adventurers in one place anyways?


To be fair, its "intended" purposes may very well be to get into prestige classes early or to allow the application of higher level spells to various things (e.g., arcane fusion, metamagic rods, war weaver's abilities).

Also it's nice for mastermind type of enemies who are likely to spend much time in their homebase (and can reastablish sanctum when they change it).

[Fouredged Sword]

To be fair, its "intended" purposes may very well be to get into prestige classes early or to allow the application of higher level spells to various things (e.g., arcane fusion, metamagic rods, war weaver's abilities).

The feat would be names "Cheese spell", not "Sanctum Spell"

Though it would have some niche application for setting up permanent effects within your sanctum. Permanency has a set cost for effects like wall of fire, web, or such spells. Being able to use heighten and sanctum spell to boost the DC by 2 to any saves involved may be a good use. You can always chaos shuffle the feats back to more useful feats after your sanctum is defended.

[Max Caysey]

Thanks... I was intending it to be used for an NPC, but I feel the same fules should apply to both NPCs and PCs.

I would seem that it can only be done because arcane fusion does not actually use slots... is this a correct interpretation?

[Fouredged Sword]

you don't expend any additional spell slots to cast those spells

Nasty combo really. Broken as all get out, but nasty none the less.

There are readings that can shut it down using only RAW.

[torrasque666]

I am right now putting together a Battle Sorcerer build that abuses it with Magic Missile. I feel like my DM won't get too upset once I tell him that a simple 1st level spell negates that.

[Fouredged Sword]

Yeah, then you get fell drain sonic snap and deal unlimited negative levels a round, no save.

[Max Caysey]

Yeah, then you get fell drain sonic snap and deal unlimited negative levels a round, no save.

Yeah... thats basically the plan!

[Vogonjeltz]

As I understand it it can only be done by some very advantageous RAW readin.

You can say that again.


Casting Time: 1 standard action

If the spell’s normal casting time is 1 standard action, casting a metamagic version is a full-round action for a sorcerer

[Metamagic]

Neither spell chosen can have a casting time longer than 1 standard action.

There's also this nugget:


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. A sanctum spell uses a spell slot of the spell's normal level.

Compare with Heighten Spell:

Unlike other metamagic feats, Heighten Spell actually increases the effective level of the spell that it modifies. All effects dependent on spell level (such as saving throw DCs and ability to penetrate a lesser globe of invulnerability) are calculated according to the heightened level. The heightened spell is as difficult to prepare and cast as a spell of its effective level.

And this:

If applying a metamagic feat to a spell, use the adjusted spell level and casting time for purposes of determining eligibility for arcane fusion.

Arguably Sanctum Spell never changes the spell level, only the effective spell level. Unlike other metamagics it uses the same level spell slot. So a Sanctum Arcane Fusion would still be a 5th level spell, rendering it invalid to use with itself.

[Extra Anchovies]

@Vogonjeltz: Metamagic Specialist, Rapid Metamagic, and Arcane Spellsurge all say hello. And they also say goodbye to the metamagic casting time adjustment.

[Necroticplague]

There's also this nugget:



Compare with Heighten Spell:


And this:


Arguably Sanctum Spell never changes the spell level, only the effective spell level. Unlike other metamagics it uses the same level spell slot. So a Sanctum Arcane Fusion would still be a 5th level spell, rendering it invalid to use with itself.

Except the things you quoted seem to defeat that statement itself:


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. A sanctum spell uses a spell slot of the spell's normal level.



If applying a metamagic feat to a spell, use the adjusted spell level and casting time for purposes of determining eligibility for arcane fusion.

That actually makes it seem more clear that this would work, assuming methods of getting around metamagic extending casting time is used.

[Vogonjeltz]

Except the things you quoted seem to defeat that statement itself:





That actually makes it seem more clear that this would work, assuming methods of getting around metamagic extending casting time is used.

That's the point, a sanctum spells level explicitly isn't adjusted. The spell is still 5th level.

[torrasque666]

That's the point, a sanctum spells level explicitly isn't adjusted. The spell is still 5th level.

You... you did read his quotes right? It outright states that the level IS adjusted, not the other way around.


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. A sanctum spell uses a spell slot of the spell's normal level.

It still uses a the same spell slot, but the level itself is adjusted. Likely intended to make it a punishment for casting Sanctum Spells outside of said Sanctum.