Broken Skies by Hannah Spencer

Twelve thousand years ago, a comet smashed into Earth.

Years passed. The world began to recover. Powerful shamans ensured such a catastrophe would never happen again.

They failed.

Livia is the last of those shamans. The world is again crumbling around her, and she descends into the darkest realms of spirit to find the way to save her dying homeland.

But every gift has its price, and Livia finds the answers she seeks because she is willing to pay that price. And now it seems the consequences will destroy everything she wanted to save.