Books in which eclipse plays a pivotal role in the supernatural plot

I am looking for dark fantasy books in which the lunar eclipse (or solar) plays a critical role in the plot, eg an ancient protagonist is in a trap but has an opportunity for escaping whenever there’s an eclipse, so a league of heroes (or villains) has to convene every time there’s an eclipse in order to avert the situation, beef up security, or the like.

That’s just an example. Please, no werewolves