A Voice That Thunders by Cully Mack

Life was simple. Place your inky hand on the rock shelter wall and transition into adulthood. You may not know your betrothed but they are with you, your clan is small. That was life until the god, Shemyaza, sent his sons to slaughter them all.
Of those who survived, Gabe is missing, and his sister Mirah is captured.

Shemyaza offers Mirah the mysteries of his heavenly kingdom. Through magic, Mirah gains secrets. As she attempts to hide her powers and the mystery behind her wielding, Shemyaza’s stepson offers to train her but can she trust him with her heart?

Shemyaza, united with four gods, a host of Giants, Wielders and Chimera, has one enemy, the destined Voice of Thunder.

Her old and new world collide and Mirah is torn. War is coming.

Whichever path she chooses Mirah knows the shadow is here, and only she can hear it whisper.