Your
PRIORITY (Destro is NOT a rotation) should be as follows:
Improved Soul Fire (You should try to have as close to 100% up time as possible, you need to try to start casting this when the buff is around 3 seconds, due to travel time of the projectile)
Immolate (don't use Fel Flame to refresh this, it's a DPS loss)
Conflagrate
Bane of Doom (Bane of Agony sucks, don't use it)
Corruption
Shadowflame
Chaos Bolt
Shadowburn (during execute phase)
Incinerate
And obviously CoE should be on the mob/boss, unless your group has a Boomkin or Unholy DK (or hunter pet, but this is less likely). If possible, like on Maloriak, use Curse of Tongues. And if you already have 8% magic damage and they're immune to Tongues, use Curse of Weakness. It almost always works on bosses and helps prevents spike damage on the tank.
Assorted other advice:
- Your neck piece currently reforges crit to hit, it should be mastery > hit.
- If you have Corla's Baton, you should be using it over your PVP wand.
- Depending on your trinket options, you should exchange the Stump for the Bell, the Heart, the Mirror, or DMC:Volcano. Stump's proc is weak, so if you can manage to get near 17% without it your DPS will go up. (Don't be fooled, you don't need 17% hit to be the highest DPS, the 372 BiS gear list for Destruction has nearly 15.5% hit but it's doing 27.5k or so on Simulationcraft.)
- Doomguard is terrible. Infernal is superior, even on single target. Blizzard is buffing Doomguard damage in 4.1 to compensate for this.
- You should be using Glyph of Life Tap instead of Healthstone (or Soulstone, but I don't know your raid comp's needs). Life Tap is a DPS increase, the others are utility.
- Fel Synergy > Demonic Embrace in terms of talent choices. There's plenty of raid encounters where your pet can die.
- Only use Fel Flame if you have the 4pc Shadowflame Fel Spark buff, or if you're moving. (And Conflag, Corruption, and Shadowflame are still on a higher priority)
- Dark Intent a Shadow Priest, Fire Mage, DPS Druid, or Surv Hunter in that order. If you don't have any of those, I weep for your soul.
- Depending on your gear and raid comp (you need the 5% spell haste for this to matter), you want to try and get 1993 haste. At that point, it easily outweighs crit as it gives you an extra tick of Corruption, so I'd suggest reforging away crit before haste.
- Also, Curse of Elements both your Bane of Havoc target and your main DPS target, it double dips and is a DPS increase, which is awesome.
I think that should help clear things up in case you were confused. Destruction is pretty difficult; I'm slightly biased, I guess, (I've played many classes/specs so I'm not that myopic) but I'm willing to wager it's one of the hardest if not the hardest DPS spec currently in the game). You have to juggle so many things at once and you can easily "screw up" your damage if you make the wrong priority decisions on the fly.
ALSO, come 4.1, unless more things change, Affliction is boss. But you still might need Shadowfury for Cho'gall if you're in a 10 man guild.