So nukers in general are in pretty bad shape right now, if you are talking about cap play R10 quests, R1 raids. FVS, in particular, got nerfed in addition to the high reaper penalty and epic strikes.
The only answer to DPS mantle is Draconic, if you want to max out your DPS I would guess it is still best to do Tiefling for fire strip, fire draconic mantle, and Ruin/Gruin with force is really the best you could probably do. You would need to gear for Fire/Force/Positive/Light, which is doable if you put some effort into it. For a strike, you might use energy vortex from Draconic.
Feats something like:
1) Maximize
3) Quicken
6) Empower
9) Heighten
12) Arcane Initiate
15) Mental Toughness
18) Improved Mental Toughness
21) Wellspring of Power
22) Spellpower Fire
24) BoGW or Embolden
25) Spellpower Force
27) Intensify
28) Spellpower Positive
30) Ruin
30) Scion of Fire
31) Spellpower Light
33) Gruin
34) Crush Weakness
Epic Destiny (83)
Draconic 35-39
Primal 25
The third destiny is pretty open, depending on what you want to augment.
You could also do the evocation line of spell focus if you feel your DC are not good enough.
If you have Dino gear and the critical chance augment from MD, Deacon + MD Augment is hard to beat. With Dino Armor + Head + Cloak, which lets you push two elements' critical damage, with a third that you can get a bit higher as well.