A book where characters face off against an ancient power

hi all,

title about covers what I'm looking for.

I want a book where the characters are fighting against some sort of ancient power, be it mythical beings, demons, gods, or anything so advanced it appears as such.

I don't really have a similar book in mind but I do prefer a faster paced book, I'm not overly into any sort of fancy prose nor do I want something that spends more time philosophising rather than telling a story

thanks in advanced