Board Thread:Game Discussion/@comment-87.212.116.195-20130626214641/@comment-2067839-20130701024802

I have gotten two sets of Sky Guardian: one from Crius + Living Flame, the second from Flamestorm Finery level 19 + Spectral Captain level 20 (gave Sky Guardian level 20). But you're far more likely to get Wind Monarch's Robes or Rocfeather.

And yes, you can only get the "plus" version from chests.