This is another ability that I believe fits well with the Sorcerer’s them. I’m still not sure if the feat requisites are fine. I wanted to simulate that a sorcerer needed not only “innate potential” (i.e. high Charisma) to attempt these actions, but also some experience (the level requirement, based on the Fighter’s mechanic for Weapon Specialization).
Your innate arcane talent is so honed that allows you to mimic other dweomers whose casting you witnessed.
Prerequisite: Sorcerer level 4th, Char 17+
Benefit: When you gain this feat choose a spell known slot. You can’t select a spell to fill this slot, leaving it opened. Whenever you personally witness a spell been cast, you can attempt a Spellcraft check (DC 20 + the casted spell level). Increase the DC by +5 for each of these metamagic feats employed: Eschew Material Components, Silent Spell and Still Spell. This check requires a standard action and can be done until 1 round after the casting.
If you’re successful and the target spell is of a level equal to or lower than your chosen spell known lot, you can copy the casted spell and cast it once. You can cast the copy spell again, but it becomes harder, requiring 2 slots. You can’t cast it a third time unless you see another spellcasting doing it in your presence.
When you copy a new spell, the “old” one can’t be cast. In effect, this feat works as if you possess and “open” spell known slot (but limited to only two castings for each copied spell).
Special: You can buy this feat more times, each time choosing a new spell known slot. If your Gamemaster allows, when you increase level and gain access to new spells known you can learn the last spell that you copied.
Eldritch Improvisation, Greater
Your are a natural magic mimic.
Prerequisite: Sorcerer level 8th, Char 21+
Benefit: You can now use your “opened” spell known to copy even spells from other classes’ spell lists. Increase the DC of the Spellcraft check by +5. You can only cast this copied spell once and it automatically requires 2 slots.
Special: Due to obvious reasons, you can’t permanently learn copied spells from other spell lists.