Twilight Knife + Surprise Spell (Arcane Trickster Cap), Sneak Attack Stack?

[BlueWitch]

Say you're a Lvl. 14 Character.

2/Wizard
2/Rogue
10/Arcane Trickster

Would the Sneak Attack Bonus from Arcane Trickster and Rogue STACK with the ones from the Twilight Knife spell itself if I have Surprise Spell?
"Surprise Spell" is the cap for AT. It says it works on ALL Spells that damage Hit Points, so long as they are Flat-Footed.

At this Level, I'd have Sneak Attack +6d6 (from Rogue/Arcane Trickster)
and the Twilight Knife spell itself is +3d6 (because its 1 per 4 levels)

That's a Grand Total of +9d6
+10d6 w/Accomplished Sneak Attacker

So, like, would this work? Is this breaking any rules? Seems kinda op actually. But I want to be sure.

Bonus Question: Would Surprise Spell work with Spirit Weapon and Spirit Ally? (You'd have to do it via Scroll)

[Psyren]

It says it works on ALL Spells that damage Hit Points, so long as they are Flat-Footed.


Twilight Knife doesn't actually deal damage though, it creates an effect ("floating knife of force") that then attacks to deal damage. If you rule that this counts as a damaging spell, then you could apply Surprise Spells to everything from Summon Monster to Blade Barrier to Planar Binding; that's not how I read the ability at all.

[BlueWitch]

Twilight Knife doesn't actually deal damage though, it creates an effect ("floating knife of force") that then attacks to deal damage. If you rule that this counts as a damaging spell, then you could apply Surprise Spells to everything from Summon Monster to Blade Barrier to Planar Binding; that's not how I read the ability at all.

Aw, nuts. Well, it did sound a little too good to be true xD
But yeah, you're probably right. Thanks for answering! ^^