Shock and awe
For optimum DPS, an Enhancement Shaman's spell cycle should be punctuated by shocks, which are instant cast damage-dealing spells that don't interfere with a Shaman's swing timer. The biggest problem with utilizing shocks as part of an offensive spell cycle is the prohibitive mana cost, which can make a dent on an Enhancement Shaman's relatively low mana pool. To alleviate this , we take 5/5 Convection from the first tier of the Elemental tree, which reduces the cost of Lightning and Shock spells by 10%.
Naturally, we would also like to give as much punch to our shocks as much as possible, making 5/5 Concussion, also from the first tier, a convenient choice. 5/5 Reverberation, on the third tier of the Elemental tree, cranks up shock DPS by allowing the Shaman to throw out three shocks every fifteen seconds as opposed to two every twelve. On the fourth tier, there's an interesting talent called Elemental Devastation which seemed to have been specifically designed to complement Enhancement. Although it's unlikely given the low spell crit of most Enhancement Shamans, even with a modest spell crit rating, 3/3 Elemental Devastation can confer a substantial 9% melee crit enough times to make the investment worth it.
In the Enhancement tree, taking 5/5 of the first tier Ancestral Knowledge is a no-brainer that boosts the Shaman's longevity in combat. While Chris' Enhancement Shaman Build Shop focused on raid utility, opting to go for improved totems, I'm going to recommend taking Improved Ghost Wolf and Improved Lightning Shield from the second tier. With the changes to Ghost Wolf in Patch 2.4, it becomes an instant cast spell that can prove to be extremely useful in maneuvering in combat, specifically PvP. Because Enhancement Shamans are always in the thick of things, taking their fair share of hits, a constant refresh of Lightning Shield should boost our DPS by a decent margin.
Because Enhancement is all about weapons, 5/5 Thundering Stikes from the second tier is another no-brainer talent. The higher the critical chance, the more Shamanistic Focus -- the next talent we'll pick up -- will proc. The more times Shamanistic Focus procs, the more shock spells we'll be able to dish out. Naturally, higher crit chance is also synergistic with Flurry, on the fourth tier. The faster our attacks, the more chances we have to crit again, and the cycle continues.
On the fifth tier of Enhancement, we'll take Spirit and Elemental Weapons to boost our offensive punch. We take Spirit Weapons primarily because it's a pre-requisite for Dual-Wield and Elemental Weapons because we want to squeeze out as much Attack Power from Windfury Weapon. Along with Dual-Wield on the same tier, we necessarily branch out for Dual-Wield Specialization, as the +6% hit will greatly ease the +hit requirements we'll need to stack on gear. On the sixth tier, we'll take Mental Quickness, which further reduces the cost of our shock spells by another 6% in addition to scaling our spell damage and healing with our Attack Power. The more Attack Power we have, the more powerful our shocks become.
On the seventh tier we'll find the key talents for Enhancement, such as Stormstrike, the only controllable melee attack a Shaman has. Stormstrike also applies a debuff on an opponent which makes them susceptible to the next two Nature damage spells for 12 seconds. With Reverberation, it's fairly easy to squeeze in two Earth Shocks within that period. More pew pew.
5/5 Unleashed Rage on the eighth tier grants more Attack Power on every critical strike, which also translates to slightly more shocking shocks. Because critical strikes also proc Flurry, there are more chances to further get crits within a shorter period of time, in theory creating a steamrolling crit and shock machine. Of course, all this only lasts as long as we have the mana to cast shocks and Stormstrike, which makes the 41-point talent Shamanistic Rage some sort of reset button. Because the chance to regenerate mana only occurs on successful melee attacks, it's crucial to stack enough +hit to reduce miss chance to the minimum.
This leaves us about four points to throw into either 4/5 Weapon Mastery or 2/2 in both Enhancing and Guardian Totems. Neither of the latter talents contribute directly to the shock and attack cycle, but provide more group utility. In particular, the Guardian Totems talent is valuable mostly for its reduction in Grounding Totem's cooldown, which will prove extremely useful in PvP. Strength of the Earth and Grace of Air will more than compensate for not taking Weapon Mastery.
The idea is go for a moderate amount of spell crit to ensure that Elemental Devastation procs often enough to raise attack crits to create the illusion of a self-sustaining engine of shocks and crits. Because Enhancement talents are designed to proc off each other, we tried to variate on the more common build by reaching deep enough into Elemental to get the one talent designed for Enhancement. It also takes talents that are tailored for shocks, the augmentative spell for Enhancement, and focuses on mana reduction to conserve our small mana pool. Played right, the build raises traditional Enhancement DPS at the expense of moderate raid utility, which should be just fine as the last thing you want to do as an Enhancement Shaman is to be spamming Healing Waves, anyway.