I figure first page will be a good place for this since we can expect a lot of questions on it (its just one of those things...):
Fel Flame: Will it ever be useful to cast? I've been throwing it in my rotation for funs sake but I have a gut feeling that the dpct just isnt worth it
Has anyone got any math/analysis on this?
It is useful. I did my first two raid fights last night, and there are multiple uses in both. In Conclave of winds, use it while getting out of ice patches on the North guy, use it to finish off last bits of HP on adds as you're running back to the slipstream after dpsing on the West platform. On argaloth, use it while strafing back and forth during rain of chaos phases, after conflag is on cooldown and refreshing corruption and bane of doom.
Edit: Also to the poster above me:
1. Demon Soul does not require Soulburn, so one's use is not dependent on the other's.
2. For Affliction, I haven't run a sim, but logically it follows that you should open with soulburn: soul fire as your first damaging spell so that all the spells that follow (including dots) can benefit from your haste. In other words, after cursing the target, the ISF buff will be the highest priority on your action list. The only caveat is I'm not yet sure which should take priority if haunt and soul fire both need to be refreshed at same time, the guess here is haunt becuase of the higher modifier (20% dmg >> 15% haste) and because of its affect on corruption refresh.