The Fifth Sorceress is so bad that reading it is a surreal experience. If you put it down, you're likely to find yourself wondering whether prose that awful actually exists or if your mind is playing tricks on you. I first read it 18 years ago and the burning awfulness sticks in my mind long after the details of a hundred mediocre fantasy novels have vanished from memory.
I'll mention the extreme misogyny, as it can hardly be avoided. Genre readers have, unfortunately, long been familiar with casual sexism, but with Newcomb there's nothing casual about it. All significant female characters are depicted as depraved, violent, sex-obsessed maniacs. Newcomb specifically states that women characters' sexual desires were due to evil magic, most particularly lesbianism. At the same time, Newcomb specifically has his male protagonist sleep around and informs us that this is fine and normal. I wouldn't so much say that Newcomb's sexism is over the top. More accurate to say that he went to the top, built a massive tower on the top, and launched a rocket upward from there at high velocity. There's obsession with rape and torture as well. Anyone likely to be traumatized by such should avoid this book entirely.
If one could ignore the raging misogyny and rape obsession (which one can't), what remained would be the worst piece of writing ever published. It utterly, totally fails on so many levels that only a small fraction can be covered in one review. I might mention the parade of tropes: the handsome prince, the beautiful and helpless princess who needs to be rescued, the Gandalf clone, the magic piece of jewelry that gives world domination, the sword with special significance, the prophecy, the inn scene, the wise elder who lives in the woods... I might mention the treacly sentences that would get rejected by a romance novelist ("You are handsome and strong and I know in my heart that you will not hurt me", "Frederick loved her more than life"), the clichés ("What he saw made his jaw drop", "This was not a man to be trifled with", "His blood froze in his veins", "I should have killed you when I had the chance"), the infodumps, the baffling choice of names (Traax, Wigg, Failee), the blatant copying of well-known lines from movies, TV, and even music ("Plant your love and let it grow"), and much more.
Let me start with the plot. Prince Tristan is about to be crowned King when an army of flying minions (officially called "The Minions") bursts into the castle, slaughters his parents and friends, steals the magic jewel, and kidnaps his Princess sister. Then Tristan grabs his sword and marches of to the villains' fortress to kill the villains and rescue his sister. That is the entire plot. There is literally nothing else. Yet once he sets this idiotically simple plot in motion, Newcomb keeps screwing it up. Time after time, he writes himself into a corner with no logical way out. Then he simply has his wizard deliver a long, bland lecture, which invariably contradicts earlier material, that's supposed to fix the plot hole but actually introduces new plot holes.
As an example, most fantasy authors have a map and make sure that there's a route on the map that their characters can take. Newcomb instead has two countries with an ocean in between, and he tells us over and over, backwards and forwards, that there's no way across the ocean. Then he realizes that Tristan is on the west side but needs to get to the east, so Newcomb suddenly declares that there's a magic portal that goes straight from where Tristan is to where he needs to be. The portal has never been mentioned before, no other portal exists, no explanation for why it exists is given, and no effort is made to explain why characters haven't been using the portal throughout the book. Elsewhere, one character is five months pregnant at the start and Newcomb needs her to give birth a few days later at the end, so he just declares at the last minute that this is a MAGIC pregnancy which only lasts five months. Presto chango, problem solved!
I might also mention the tome officially called "The Tome", the ghetto officially called "The Ghetto", or the author's utter ignorance about swords, horseback riding, and so much more. Then there's the modern anachronisms constantly intruding into this pseudo-medieval world (the word "psychological" is used on page 4), the plague of adverbs ("he asked reverently", "he said simply"), and the basic logical errors, as when Tristan first suggests using "death enchantments" and then later doesn't know what a "death enchantment" is. Literally everything that can done wrong in a novel is done wrong in this one.
There's an old story in the sci-fi/fantasy community in which an established author sets out to write the worst novel imaginable and submits it under pseudonym, and a publisher eagerly prints it and even requests sequels. Given how The Fifth Sorceress mangles every possible aspect of writing to a degree unmatched in publishing history, some will feel that it must have been an intentional parody. So if "Robert Newcomb" is a pseudonym for a serious author, and if this was intended as a parody, and if the author happens to read this review, I would just like to say: well done and you deserve a Pulitzer.