Balancing incantatrix

[Kimerus]

Hello all!
One of my PC want to play a character 5 wizard/10 incantatrix/5 archmage. I've read a lot of discussions about the fact that the incantatrix is overpowered. We use the player's guide to faerun version, 3.5. Another PC has a dweomerkeeper, which I have weakened avoiding him to use wish without material components. It would be necessary to weaken the incantatrix too? The party is very optimized so I was thinking:
- Spell progression 9/10
- Totally remove improved metamagic (or daily uses. I don't know)
- Halve the attempts of the various sop abilities based on spellcraft. (he would have 12 attempts/day. 3+9 (int. mod.)
How would it be so? Still too overpowered? Excessively weakened?

 

[Dandu]

The main abuse of Incantatrix comes from the metamagic const reduction ability, Instant Metamagic. (Though I should note that there is errata stating that it can't be used on something whose adjusted spell level you could not cast.)

Co-Operative Metamagic can also be quite powerful. If you need to nerf something, I would start with those two.

 

[Neonchameleon]

Are you planning on playing at level 20? And what's the rest of the party?