Andre Norton's "Storm Over Warlock" was first published back in 1960 and is the first in her "Forerunner" series. It's one of several of her pre-1964 books that, for some reason, have fallen into the public domain. By 1950/1960 standards, it's a pretty good book (good writing, plot, world-building). By today's standards, it might be a little thin or linear. There's nothing wrong with it, it's just a good, straight-forward book. One thing, though: I can't figure out if it's a Young Adult book or not. There are a lot of YA elements in the book, but the writing does seem more mature than what passes for YA these days. In particular, the protagonist seems a bit old for YA (he's actually a young adult instead of the old child they use these days). I guess that's a good thing. There's nothing in the book that would preclude young people from reading it, and the writing is mature enough that we oldsters can enjoy it too. I'm rating it at a Decent 3 stars out of 5.
The novels in Andre Norton's "Forerunner" series are:
(includes "Storm Over Warlock," "Ordeal in Otherwhere," and "Forerunner Foray")
The Forerunner Factor
(includes "Forerunner," and "Forerunner: The Second Venture")