In PF, the Arcane Trickster's capstone allows you to add your sneak attack damage to any spell that deals HP damage, so long as the targets are flat-footed to you. Stone Call is a level 2 spell with medium range, that does 2d6 bludgeoning to everything in a 40' radius, with no SR (conjuration!) and no save. Depending on how your DM reads the ability, you may need Sniper Goggles to apply SA at range over 30ft. It also works with Bludgeoner, if you want to deal nonlethal.
Unfortunately, it specifically calls out that the targets have to be flat-footed, so it's only really good as an opener (Snap Shot talent and Surprise Attacks talent, etc). Being invisible means those who can't see you lose their dex bonus to AC, and being flat-footed also means they lose their dex bonus to AC, but as far as I can tell being invisible doesn't actually make them flat-footed.
Still, medium range, 40' radius sneak attack (and potentially Str/Dex damage or bleed) is pretty nice for a 2nd level spell.