Spell perfection and total modified level.

[Reynolds-sama]

So guys, i've found 2 different interpretations to this feat:

Benefit: Pick one spell which you have the ability to cast. Whenever you cast that spell you may apply any one metamagic feat you have to that spell without affecting its level or casting time, as long as the total modified level of the spell does not use a spell slot above 9th level. In addition, if you have other feats which allow you to apply a set numerical bonus to any aspect of this spell (such as Spell Focus, Spell Penetration, Weapon Focus [ray], and so on), double the bonus granted by that feat when applied to this spell.

I'm not using any trait like, Magical lineage

-> Some say that you must calculate the spell slot before using the feat.
Example: Heal spell (6th level) + Quicken spell (+4) = 10th level slot, so the feat cannot be used with this combination of spell and feat.

-> Some say that the previous example works because, the limit is set just to avoid too many metamagic feats and that the resulting spell slot would still of 6th level, and this would allow you to apply more metamagic feat, until you have enough slots.

Who's wrong?
Can you make an example about the correct use of this feat?

[andreww]

I have always taken it as including the "free feat" in deciding overall level. Quickened Heal would not be possible without Magical Lineage.

Spell Perfection is already crazy without allowing people to layer yet more metamagic effects on for free.

[Drachasor]

I agree with Andreww. It's the only reading that makes sense. There'd be no reason for that text at all if you weren't counting the free metamagic effect (couldn't go over 9th anyway!). And allowing quickened 9th level magic would not be good.

[PathlessBeth]

In particular, for heighten, your reading would allow for infinite save DCs and durations.

The real question, though, is whether you can add a second metamagic feat after applying your spell-perfection feat. So if you have Quickened Enervation (spell perfection) and then want to add maximized, the resultant level would be 7th level. The question is whether this is allowed: The spell starts 4th level, then gets quickened to 8th level, then spell perfection brings it back to 4th level, then it is maximized. At no point does its level exceed 9, but without spell perfection you wouldn't be able to do this. So is it allowed?
Based on RAW alone, I think yes, that combination is allowed. I might or might not house-rule it to not work--it does cost a bunch of feats, and aside from a few potent spells like enervation, most of the mid-low level spells which could benefit from multiple metamagic spells are blasting spells, and those are really underpowered compared to other spells to begin with.

[Reynolds-sama]

I think it's not allowed, since the requirement of the total spell level, must be met before applying any single feat.
You can't apply feats in a particular order...they're applied all at the same time, and so you have to meet the Spell Perfection's requirement.