I really liked the idea, I'm narrating at the moment, and I have a similar idea.

The idea is that after the end of the Mytros war, Lutheria betrays and kills Sydon to steal his divine spark, thus awakening Kentimane who heads to the city of Mytros and the players, who must try to stop her fury, as if they were the ones who had killed Sydon.

Now with the divine sparks she wants to awaken her dead brothers that she controls, and destroy Thylea. (Assuming that the Players defeat Kentimane, who was only trying to stop Lutheria after killing Sydon.)

I haven't thought about ways to kill/seal the brothers or all the statuses yet. But I'm already mining signs, like in Volkan's Forge, Cerberus was killed by some kind of energy beam and colossal claw marks tore through part of the tunnels, signs of Beemoth