Dragonwrath, Tarecgosa's Rest does have a proc, but the information hasn't been included in the PTR data files yet (which means there's nothing to datamine right now).
We did, however, hint at what the proc will be in our 4.2 preview:
Patch 4.2 Preview: A Legendary Engagement - World of Warcraft
The great staff duplicates destructive magics, and also bestows upon its wielder the ability to transform into a member of the Blue Dragonflight.
Also, please keep in mind that some items on the PTR are still considered "works-in-progress," so certain aspects of their design -- including stats, on-use abilities, and appearance -- may change before the next patch goes live.
Oh! And just to clarify (since I saw this asked in another thread), Dragonwrath will not be BoE.