Originally Posted by
Yvaelle
Echo or Ancestral Swiftness IMO. Echo adds more burst, Ancestral Swiftness gives you more on-demand power. Elemental Mastery is a very powerful ability, particularly for RBGS, where Ascended Ele Shamans are the new I-Win buttons for highly contested nodes like EotS-mid and Gilneas-WW.
For Arenas, AS is probably the stronger choice - but Echo is going to give you random damage spikes, which make your burst spikes more lethal - both are strong - AS obviously requires more micro - but is generally stronger.