Benjamin Medrano‘s Ancient Dreams series consists of a main trilogy, an epilogue of sorts, and a sidestory novel.
The main series is dark high fantasy with a heavy focus on corruption, secondary paranormal romance aspects, and minor dungeon core elements. It stands out mainly for not having a single protagonist (instead choosing to swap between various points of view across multiple factions) and for having an assortment of truly evil antagonists. The level of darkness is no joke either with there being a significant focus on the process of both inflicting and taking advantage of mental slavery (in notable comparison to the author’s Eve of Destruction series, which only deals with the aftermath).
The first two novels are easily the high point with the third kind of getting lost in the weeds of the martial conflict while also introducing a rather large number of minor characters which sort of dilute the impact. The fourth novel continues from where the third left off but primarily centers on resolving the remaining issues surrounding the goddess; it’s not particularly dark and also leaves a few dangling story threads for potential later novels. Personally I thought it was on par with the first two, but if you’re not interested in the religious conflict it will probably end up quite boring.
The sidestory novel, Marin’s Codex, is a bit difficult to pin down. It starts and ends with segments taking place after the main series, but the majority of it is a flashback to the end of Sistina’s mortal life millennia before the series began. It can be read as a stand-alone (if the darkness of the other novels is an issue) or as a prequel, but I think it works best if read after the third or fourth novel. In addition to that it also includes a pure-prequel novella-length telling of Sistina’s namesake’s encounter with the Nymph queen, which honestly doesn’t really add anything to the series and I’d actually suggest you skip it.