Talent setup:
Backdraft/Roaring Blaze*
Mana Tap
Eradication
GoServ (worth mentioning that even if you choose to not press the GoServ ability a single time during an encounter, it's still better than any other option on single target.)
Soul Conduit**
Opener:
-5 Mana Tap
-4 Life Tap
-3 Incinerate
-1 Immolate
0 Conflagrate (assuming you run Backdraft don't just throw these out whenever, you want to try follow it up with Chaos Bolt + Incinerate (that's currently all you can fit into one proc) and try to avoid back to back usage of both charges, this is an exception to be able to DG + Imp right away with your opener procs)
1 Doomguard
2 GoServ Imp
3 Incinerate until 3-4(?) shards are available, start CBing and try fit in as many as you can until procs are gone.
Standard rotation:
CB 2-3 fillers CB, to try to keep as high up time as possible on Eradication.
Weave in immolate, mana/life tap, conflag as needed.
Keep a 100% uptime on immolate and Mana Tap and never cap charges of Conflagrate, DG and GoServ imp as they come off CD.
The Eradication buff works very similar to previous Demonology shadowflame clipping where you cast HoG, then you cast 2-3 spells then you cast your 2nd HoG to get maximum uptime on shadowflame.
Don't just throw out single CBs randomly, always sit on a few shards and try to streak at least 18 seconds of Eradication each time, the better RNG you get, the longer you will keep the debuff up each time. (we have so much RNG, RNG won't matter amirite)
Try to time your Mana Taps before you Life Tap as Mana Tap is based on your current mana %, making it more efficient at lower mana.
Dimensional Rift seems weak and not even worth using a global on atm, expect that to change though.
*I'm not too sure what to pick here, both seems underwhelming as the buff from Backdraft currently only lasts 3 seconds instead of the 5 seconds that is mentioned in the tooltip which might make Roaring Blaze the better choice on single target, however playing Roaring Blaze forces you into the old dot refreshing style where you can't rely on pandemic dots, it also requires you to hold a conflag charge for every immolate refresh to instantly buff it up.
**Channel Demonfire is garbage, on multiple targets Wreak Havoc looks very strong on first sight, but remember that we no longer gain much single target damage with Havoc making Soul Conduit the superior choice in a lot of of scenarios more than just single target assuming 1 target is more important than the other, Wreak Havocs main use is on a fight where 2 targets are of equal importance in priority and at least one lasts a certain amount of time before dying.
This is just my initial "theorycrafting" after trying out the spec for a few hours on alpha and I have personally not completely mastered the playstyle, don't hang me if something is incorrect.