Arcane Thesis question.

[D4rkh0rus]

So, how does it work with metamagic stacking?, what Do I mean by this? What happens when you apply multiple metamagics to an Arcane Thesis spell?

For example, given Empower (+2) Maximize (+3), Split ray (+2), Twin spell (+4), Invisible spell (+0), Energy susbstitution (+0) on a scorching ray (with thesis on it)

Scorching Ray is a lvl 2 spell.

Would the final slot necesary be 9th? (Empower +1, Max +2, Split +1, Twin +3, Invis +0, Substi +0 for a +7)
Or would it be 7th (Emp +1, Max +2, Split +1, Twin +3, Invis -1, Substi -1 for a +5)

I think there was an errata, but cant find it.

[OldTrees1]

RAW: 7th
In reality: DMs will likely nerf it to 9th

[Sith_Happens]

Or would it be 7th (Emp +1, Max +2, Split +1, Twin +3, Invis -1, Substi -1 for a +5)

This, so says the errata that you can't find but is in fact right here (http://archive.wizards.com/default.asp?x=dnd/errata).

[D4rkh0rus]

I see, does this also apply to incantatrix's 10th level ability?