1D2C is hilarious with Firebrand on your team.
1) Get 1D2C.
2) Release 1D2C.
3) If your opponent blocks (or gets hit - basically don't whiff), cancel into Stalking Flare.
4) DHC into Luminous Body.
5) UNLEASH THE UNBLOCKABLE!
Firebrand and Dormammu have some solid synergy together. It would be even better if either of them had a good assist. Dark Hole isn't too bad if your opponent doesn't have mobile characters on his team though, since you can snapback-juggle between them. If my opponent is using something like Hulk/Nemesis/Sentinel, the first time I touch Hulk or Nemesis he ought to start thinking about how Sentinel is going to come in, since that is the next time he'll get to fight back.
With Firebrand around, I only end combos with Chaotic Flame if it will kill my opponent. Otherwise I end with Stalking Flare -> Luminous Body. With Firebrand on point, I TAC to Dormammu or do Dark Fire to Stalking Flare, XFC, charge 1D2C, let it go and kill my opponent. If Stalking Flare kills, charge 1D2C, unleash it on the incoming character, and then raw tag to Firebrand to start it all off with some free chip and blockstun!