Book Four of The Wielder Diaries.

Tightening my grip, I whispered against the winds, "Find help, Nan. Hurry."
                         *
"Air Attuning, its magic, is the weakest by far."
                         *

The light of the crystal flickered.

Reflecting under the sun, a glittery trail of chipped material fell down the tower's side.
                         *

Time...we had time. 

Numb, the noise from the world had fallen away.  

~ Time warps and mysteries deepen. Our heroes struggle to unite and face a terrible choice among revealing twists.