Your spells are particularly effective against those caught unawares.
Benefit(s): During a surprise round, your opponents that have not yet acted take a –2 penalty on saving throws against spells you cast. Creatures that have already acted take a –1 penalty during the surprise round.
Can anyone think of any reason this wouldn't work when casting spells like Dream Scan, Nightmare, Demand, Scrying, Create Mindscape (when they can't see you), or any other spells that effect targets without line of sight? We don't ordinarily think of this as a surprise round, but it kind of totally is, as the subject could roll initiative right after to try a defense or reaction to the spell that just hit them.
Seems like a pretty powerful option for certain patient mastermind or long-range spy builds, not just the guys who open combat from a Greater Invisibility. Also great for Cunning Caster when you succeed in casting the spell unawares.
While I would not have a problem for it as a GM, and it makes perfect sense that this could work thematically, technically by mechanics the time you are using the spell is not a "Surprise Round" (at least for some of the spells you mentioned).
"Surprise" is a sub-section of combat. Because a combat doesn't happen there is no surprise round. So spells like Scrying which will not result in a combat cannot make use of this -2 on saving throws.
However spells that would result in a combat starting (such as Create Mindscape) can benefit from this feat, but ONLY if the person your using it on fails to notice you casting it. If they succeed in noticing you casting it, there is no surprise round because a surprise round only happens when combatants fail to notice a combat starting.
For Reference:
When a combat starts, if you are not aware of your opponents and they are aware of you, you're surprised.
Determining Awareness
Sometimes all the combatants on a side are aware of their opponents, sometimes none are, and sometimes only some of them are. Sometimes a few combatants on each side are aware and the other combatants on each side are unaware.
Determining awareness may call for Perception checks or other checks.
The Surprise Round
If some but not all of the combatants are aware of their opponents, a surprise round happens before regular rounds begin. In initiative order (highest to lowest), combatants who started the battle aware of their opponents each take a standard or move action during the surprise round. You can also take free actions during the surprise round. If no one or everyone is surprised, no surprise round occurs.