D&D 5E Sorcerer6/Rogue3 crazy burst question

[faria]

I'm currently a fire dragon Sorcerer 6, thinking of dipping into Rogue for Assassinate at level 3. I think Sorc6 is the sweet spot to begin the Rogue dip because I just picked up Elemental Affinity. Elemental Affinity gives me CHR mod damage bonuses on my spells, and it kicks in for EACH ray of Scorching Ray too. That adds a crapton of damage! Assassinate would also boost the out of Scorching Ray because it gives advantage on EACH ray, which I have to roll separately.

My questions are:

1) If I use Scorching Ray while hidden to start a fight, would all the rays crit or just the first?

2) Can I Twinned Spell it for even more burst?

3) If I CAN Twinned Spell it, would all the rays from the second one also crit?

4) If I used Quickened Spell instead, would they still be surprised after the first spell went off (therefore making the second spell crit too)? What if I target a different enemy with the Quickened Spell (will the second enemy still be surprised)?

5) Would I be able to add Sneak Attack dice to any of these surprise spell attacks?

6) Is there anything I'm not considering? Is this build viable/worth it? Can someone do the math and tell me if the damage increase is significantly more than a straight Sorcerer9 can dish out?

 

[Choronis]

Unfortunately, the errata has clarified a lot with regards to Twin and Elemental Affinity. Check it out here: http://media.wizards.com/2015/downloads/dnd/Errata_PH.pdf

You are no longer able to use your CHA mod to each Scorching Ray. Only 1 ray gets the added damage.

1) Only on the first ray. Because you are making multiple attacks, the first one only gets the benefit of surprise.

2) Scorching Ray isn't able to be Twinned, as of the latest errata

3) See 2

4) Again, only the first spell that hits them would gain benefit of surprise, regardless if it was the Quickened Spell or not. Attacking, whether you hit or not, will reveal your position. So even if you target a different enemy, they would not be surprised anymore.

5) Yes. The first one you attack.

6) This build would've been more viable before the errata. Because of the clarifications on Twinned and Elemental Affinity, you're definitely better off with Sorcerer 9. You get level 4 and 5 spells that way. Level 4, especially, is good for Sorcerer.

 

[Coredump]

Chronis has a few things wrong.

1) Being hidden does not lead to an auto crit, just advantage.
If you are only hidden, then you get advantage on the first attack of the round.
If you are a Rogue(assassin) and your target has not gone yet**, then all of your attacks will have advantage
If you are a Rogue(assassin) and have a higher init than a *surprised* target, then all of your attacks will have advantage, and all auto crit

**Either because you are going before his first turn, or because you are going after his first turn, but he was surprised.

4) As with 1), the advantage/auto-crit would apply the same to both castings. But remember.... if you cast a spell as a Bonus Action, any other spell you cast must be a cantrip. This trick doesn't work with 2xscorching ray.
If you target a different creature, then you need to apply 1) to that creature to determine what happens.

5) No. You never get SA with spells.

6) Hex/Hunter's mark? Paladin smites?

 

[faria]

Thanks for the answers. Kinda disappointing, but okay, 4 followup questions:

1) What is the strongest single target SORCERER spell that would stack with Assassinate before level 10?
2) What is the strongest single target SORCERER spell that would stack with Assassinate after level 10?
3) What is the strongest single target ANY-class spell that would stack with Assassinate before level 10?
4) What is the strongest single target ANY-class spell that would stack with Assassinate after level 10?