This omnibus collection, a rewriting of three novellas from the author, is a prequel to another, somewhat more popular trilogy called the Complete Book of Swords. It's not necessary to read these books before the Swords trilogy, but there are hints and allusions to the events of this work. It follows a familiar plot: small humble farm boy gets caught up in a resistance against a powerful empire. The first book follows the farm boy, Rolf, as he joins a small band of resistance fighters who are currently fighting against a local satrap (Dictionary.com tells me this is a "governor of a province under the ancient Persian monarchy"...why this term was used in the novel as opposed to Duke like in the Swords novels is never explained). In book two, the resistance has grown, and goes against the next level of the hierarchy, Som the Dead. Here I should mention the story shifts heavily away from Rolf in the second novel, focusing more on Chup, a minor character in the first novel who becomes a sort of antihero. The final novel (back to Rolf) has the army, now under the leadership of a prince (or was he the leader the whole time but not introduced until book 3? That's unclear), going against the Emperor himself.
The books are typical of the genre, with wizards who have vaguely defined abilities, demons and mythical creatures (eg the resistance has "Birds", which are apparently giants now, but only come out at night, whereas the evil empire has "Reptiles", which can fly but are only out during the day), and also adds a little bit of some sci-fi, as there are instances of "Technology" from the "Old World".
For these books, it's important not to get caught up in small details, and just enjoy the ride. Characters that seem to be important are dropped, there are a few plot holes. But the overall arc of the story is enjoyable, if definitely a relic of its time. The series was written during the Cold War, and the whole West (the good white guys) vs the East (the evil empire, who are vaguely Asian).
A few random notes...SPOILERS FOLLOW
* Thomas, the leader of the local resistance, was definitely set up to be more of a character in the first book. And whatever happened to his lady friend from the first book? ALSO, I legitimately thought Thomas was Prince Duncan and either Saberhagen didn't bother to change his name in the re-write, or maybe he took on a new name, the way some British royals do...until he got a one sentence mention towards the end.
* Mewick was made to seem interesting but his character went nowhere.
* So they didn't try to save the Elephant?
* The way Som was defeated in the second book might have been one of the most unintentionally funny things I've ever read.
* The Djinn was some plot device nonsense.
* So Ardneh was a computer program who became sentient, and somehow telepathic?
* Charmain, seeing Rolf near the beginning of book three: "realizing he was the one person that probably could have truly loved her"...WHAT?!?! They barely knew each other!