Solution

As soon as everyone emerged from the dungeon, the shaking of the earth only became stronger, more frequent, and more violent with the passing of every minute. 

Everyone could tell how fierce the battle being fought was underground. 

Evie kept her eyes closed, watching the battle through Onyx's eyes. Gav looked like he had fully and thoroughly lost his mind. He was laughing like the ultimate villain who had decided to play with his prey, torture them with his unrivalled power until he was satisfied, before finally delivering the final blow. There did not seem to be even a sliver of Gav's personality that could be seen in him at this moment as Evie watched on. Though her heart ached painfully, and she was incredibly tempted to break down and wail out in mourning of the loss of his soul, she hung on. She believed that he was not truly gone as how he appeared to be on the surface.