A Court of Earth and Aether by Meg Xuemei X

Cass Saélihn is the weapon, the hybrid born to kill the Olympian gods.
Only the price is her own life.
One dies so millions can live. So her mates will live.
But Cass can’t just abandon them, can she? She’s just found them–a home she’d never imagined she could have. So when Death offers her a way out if she plays one of his sick games, she can’t refuse. If she plays it right, she might just rise from ash and ember.
And her loyal warrior-mates will be with her in life, or death. Even when she has to become the Darkness that devours the worlds. Even when she’s lost to herself.
She’s not lost to them.
So, she’ll play the final deadly game, and when Cass unleashes her true, powerful self, the immortal gods will burn in her flames.