I've said in the past that enhancement is in a good place in 4.3, and that's the truth. Despite some really awful itemization and some as-yet-unresolved issues with the spec, enhancement is remaining a strong middle-of-the-pack contender. In non-cutting-edge raid groups that don't have multiple Dragonwrath-wielding casters, we're even better.
Dragon Soul is a great instance for enhancement in 4.3 because it offers a variety of fights. Some play to enhancement's strengths, some highlight its weaknesses, and some fights are Ultraxion and your DPS spec doesn't matter, provided you can push buttons and click a shiny purple dot on his screen every 45 seconds. For the purpose of brevity, I'm going to assume you're familiar with the normal-mode mechanics of these fights (and if you're not, some are conveniently covered by my frenemy Tyler Caraway in the Ready Check column) and just speak to how enhancement specifically fares on these fights.
There's nothing particularly special about Morchok for enhancement, except if you're doing the fight on heroic. Shamanistic Rage and Glyph of Stoneclaw Totem make Morchok's Stomp damage negligible, but Stomps don't really hit hard enough on normal to worry about. However, if you have a healer in line of sight during a black phase (and you've done nothing in recent memory that would cause them to hate you), Glyph of Stoneclaw Totem and Shamanistic Rage will let you stay on the boss for most if not all of the phase. If you don't have a friendly healer, enhancement still fares better than most melee on this fight, as cast Lava Bursts and Lightning Bolts still hit hard.
Zon'ozz a trois
Warlord Zon'ozz introduces us to Dragon Soul's favorite anti-enhancement element: burst damage. Enhancement is great on the parts of this fight that don't take place in a black pool of ooze -- i.e., the phase where you get to stand still and chop hard with your No'kaleds. Unfortunately, Feral Spirit is still one of the most awful DPS cooldown in the game, and we can't bring the hurt in black phase the way a fire mage or a retribution paladin with Avenging Wrath up can. Enhancement definitely won't be topping meters here, but it's also not a fight where our lack of burst is a huge issue.
Yor'sahj the Unsleeping is an interesting fight for enhancement. In one regard, it confronts us with our ancient nemesis: target switching. Moving and rebuilding Searing Flames stacks is never our preferred method of DPSing, but we'll take it because this fight also highlights one of enhancement's newfound strengths: prolonged AoE phases. Since Yor'sahj's Forgotten One minions tend to stay out for a good 15 to 20 seconds, it's fairly easy to get off two spreads of Flame Shock with Lava Lash, which leads to a lot of juicy, Fire Nova-ey goodness. While Combustion-spreading fire mages and Felstorming demonology warlocks will probably beat you, rest assured that you're one of the stronger DPS classes for this fight.
Hacking it on Hagara
There are a few annoying aspects about the Hagara the Stormbinder fight. First, her Ice Lances slow melee attack speed on every stack, which means less DPS for you if your ranged players are awful about not standing in the blue beam. Second, she also has a short, Zon'ozz-esque Feedback phase where she takes considerably increased damage, once again highlighting our lack of burst. Finally, there's a lot of target switching in this fight, be it Ice Tombs, Frozen Binding Crystals, and Bound Lightning Elementals.
Ultraxion is a fight where enhancement shines just as brightly as every other DPS class in the game. Due to the extreme lack of mechanics involved for DPS to deal with, there's not much benefit to be lost or gained from including an enhancement shaman in your raid comp.
That said, running the Raid Finder version of Ultraxion as enhancement is fun, as well-timed Shamanistic Rages and Stoneclaw absorbs means staying above 100k hit points during Hour of Twilights, earning you some nice extra DPS time and the ire of all your healers. (Except for me. I love people who stand out on Ultraxion, as the first 4 minutes of that fight are super boring to heal otherwise.)
Mastering the Warmaster
The problem of bringing an enhancement shaman to the sixth boss of Dragon Soul is the same problem that afflicts melee players on this fight in general -- that is, it's better to stack ranged to take him down. Ranged DPS who can multi-DoT the melee adds and focus down drakes while soaking the purple swirls are a better choice to bring, in general.
That said, enhancement's cleave damage on this fight is pretty good, and there are almost always adds alive for melee to attack (and if there aren't, tell your ranged DPS to step it up on those drakes). We can do some pretty nice damage and have the benefit of being melee when Blackhorn actually descends to the ship's deck. Also, I know this line is getting tired because I've been saying it since Cataclysm first hit shelves and I took over Rick Maloy's spot as the enhance columnist, but enhance survivability is amazing. Use your cooldowns effectively, and you'll be a valuable asset to your raid here.
Chiropractice for Dragon Aspects
Make no mistake: Despite the abundance of long-lived adds, and the high damage Nuclear Blast phase that we can Shamanistic Rage through, Spine of Deathwing is not an enhancement fight. In fact, Spine is actually the worst fight in Dragon Soul for enhancement, particularly if you're on heroic mode. Heroic mode isn't the only one with a strict DPS requirement, though, and enhancement's status as the worst burst class in the game makes us incredibly hard sells to any serious raid team. This is the only fight in the instance where being sat for your spec choice is a real possibility. (Though fights like Zon'ozz or Blackhorn favor ranged on heroic, that's a melee vs. ranged debate. Spine is the only fight where enhancement is singled out for being enhancement.) On the plus side, chances are you'll be included again once we get to Madness of Deathwing.
Making it on Madness
Madness of Deathwing happens to be my favorite fight in Dragon Soul and probably my favorite fight of Cataclysm. Yes, you can yell at me in comments for admitting that. I'll also admit that the Lich King was my favorite fight in Wrath of the Lich King, which will probably make all of you dear readers doubt my sanity.
Beyond that, enhancement's AoE is really highlighted on the Regenerative Blood phases, particularly when Nozdormu's been taken out of the fight and his time zone is no longer around, though you do need to watch your timers so as to not waste shock or Lava Lash cooldowns before Hemorrhage. We also have beastly survivability cooldowns for Elementium Bolt and other high-damage phases. On the downside, we definitely scale worse with some of the dragon aspects' buffs, such as Nozdormu's 20% haste buff.
Show your totemic mastery by reading Totem Talk: Enhancement every week. We've got enhancement-specific advice on the latest gear and tier gear set bonuses, and we'll help you dig in and learn to level the enhancement way.