Just had a few questions about the destro rotation:
First and formost, should i manually cast SF to keep up improved SF, or should i wait for it to proc?
Second, should i manually cast immolate to keep it up or should i only refresh with fel flame (while not moving)
Third, should i use the increased 30 percent cast time from conflag to cast 3 incinerates (and manually cast choas bolt) or 2 Incinerates and 1 choas bolt?
And then just ignore backdraft, it's a nice bonus to have your cast times reduced, but just ignore it. Half the time when I played destro I still had a stack of backdraft between movement and other things up and it just doesn't matter.
Yes. Manual cast SF when 3 secs are left on the buff. If it happens you get a proc, then you get a free SF right after the casted SF. It is what it is, but its worth it to cast the SF than to let the Imp SF buff fall off.
Yes. Manual cast immolate. It does more damage than just refreshing it with Fel Flame. The only time you should ever cast fel flame is if you have 4 piece T11 bonus proc.
It doesn't matter. You should be casting CB every time it is off cooldown, regardless whether it is a backdrafted one or not.
Soul Fire - Yes you have to manually cast soulfire. You should begin casting it when you have about 3 seconds left on the buff. I have a power aura that lets me know when I have 4 seconds left on it so I can finish what I am casting look and then cast soulfire. The only time you don't really need to cast it 3 seconds prior to it falling off is when you know you are going to use soulburn + soulfire to make it an instant one. I usually use soulburn + soulfire as my first one and save the other two to use throughout the fight.
Immolate - Never use Fel Flame to re-up it - it's totally a dps loss. The only time you should be using Fel Flame is if you have the tier 12 4pc set bonus & it procs or if you are moving and all of your other DoT spells are up.
Backdraft - Just do what the other two posters said and ignore it.