Looking for specific feat

[Korivan]

There's a feat that let's you swap out spells as a wizard. Think it requires spell mastery. Anyone know what it's called and where it is?

[Karmea]

Uncanny Forethought from Exemplars of Evil?

[Biffoniacus_Furiou]

Uncanny Forethought, from Exemplars of Evil. Leave spell slots open, cast Spell Mastery spells from them as a standard action, or cast any spell you know from them as a full-round action.

Signature Spell, from Player's Guide to Faerun. Pick one spell you've mastered, you can spontaneously convert prepared spells into that spell like a Cleric or Druid spontaneously casts Cure or SNA spells, respectively.

I think there's a worse version of Uncanny Forethought somewhere, probably CA or CM, that allows you to only leave one spell slot open per day and do basically the same thing. Uncanny Forethought allows a number of spell slots equal to your Int bonus each day.

[Korivan]

Uncanny forethought, that's what I was looking for.