For enhancement, you take on the form of an air Ascendant, making your melee auto-attacks and Stormstrike become ranged attacks that are able to be used at up to 30 yards away. They also deal pure nature damage, which means they're benefited by Enhanced Elements and ignore armor. From a PvP standpoint, melee attacks from a 30-yard range that ignore armor will be frustrating for escaping clothies and plate-wearers that you're trying to keep your distance from.
Elemental morphs into a fire Ascendant. In this form, your Chain Lightning morphs into Lava Beam. Lava Beam is similar to Chain Lightning but hits a total of five targets and doesn't reduce its damage when it jumps, which is potent AoE. For single targets, your fire Ascendancy makes your Lava Burst have no cooldown during its duration, which means back to back critical hits for 15 seconds.
The last Ascendant form is restoration's water form, which functions very similarly to the Essence of Dreams in Ultraxion. For 15 seconds, every heal you cast duplicates its healing done and splits that secondary healing amount among all nearby targets. If you cast a 100k Greater Healing Wave on your tank, she'll be healed for 100,000 and another 100,000 healing will be split among allies near her. It's very potent.
If you want more in depth views of Ascendance and the benefits and cons, Joe Perez and I recently wrote Totem Talks covering Ascendance for DPS and resto shaman.
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!