If you'd like a primer on how to write a synopsis, see my posts here and here. And if you want your synopsis critiqued on this website, fill out the form here, or email your 1-2 page synopsis to me at firstname.lastname@example.org, and I'll post one critique per week (NOTE: I'll email my critique to the author as soon as I'm done, so the author won't have to wait to see his/her synopsis on the site). Thanks for participating!
K-ONE lives in the steel Tower of Resteth. She is a “baldra,” a young woman who has survived a fatal illness. [Thank you for explaining what that term means right up front!] The ten baldra of the Tower act as servants to their upper class masters, allowing their blood to be harvested for cure research in exchange for the NEN, a mind-fogging medicine which keeps them alive. ['Nen' doesn't have to be in all-caps here, since it's not a character. If it's a proper noun, you can just introduce it as 'the Nen' or, as I suggest below, leave out the name and describe it as the potion, medication, etc.] [This is a nice, clear first paragraph. We're given K-1's 'normal life' and you do quite a bit of world-building with not very many words.] During an errand, K-1 crosses paths with the ruthless Tower leader RIDER, who is genial to her despite her loss of temper. [Why did she lose her temper? If she's a servant and he's ruthless, and she depends on him to stay alive, wouldn't she try to hold her temper? We may need a few character details about K-1 earlier to feel comfortable with this.] Now having doubts about his character, K-1 feels impotent, terrified that she is missing something. [This seems like an odd reaction to finding out Rider is actually a nice guy. Does he also seem to know things about her? Is he trying to get her to do something for him? Why does she feel like she's missing something?] In voicing this fear, she provokes an unexpected voice in her head to speak. [Is this the first time she's heard voices in her head? If so, say that. If not, give the reader a hint that this is something that happens to K-1 a lot] The voice is XABRIC, a prisoner of the Tower. He senses magic inside her, and suggests that she use it to escape with him. K-1 refuses to trust a captive. [But she's kind of a captive herself, isn't she?] The next day, K-1 again sees Rider, but he hits her in front of other Tower leaders in a vicious display. Tormented by this reversal, K-1 is then tasked with cleaning Dungeon cells near Xabric. [Has she met Xabric before she heard his voice in her head the day before? If not, how does she know it's him?] She can hear it as he is tortured through other people’s bodies. [What does 'tortured through other people's bodies' mean?] After, he explains in mind-speak that when he looks in someone’s eyes, he can control and speak to them. As he has never seen her, their connection should thus be impossible, although he cannot control her as is. Xabric then declares the Nen a lie. K-1 is unnerved, but though she pities him, she is still resolute not to help him. [Why?] Later, K-1 comes across another baldra who has been beaten nearly to death. K-1 barely saves her life with what she believes is Nen, but turns out not to be. [What is it? How does K-1 discover it's not Nen?] Suspicious of the Nen and angry at her masters’ senseless violence, K-1 purposely goes the fatal amount of time without Nen. When she doesn’t die, she offers to help Xabric escape, if he will help her get all ten baldra out of the Tower with him. He says their best chance to escape is during the upcoming holiday, Omniren. [There are a lot of names/terms specific to your world in this synopsis, which can quickly get confusing for a reader. For those that are less important to the plot flow, I suggest omitting the proper nouns and describing them. 'Omniren' can just be 'the upcoming holiday.'] With less Nen in her system, K-1 spies on the Tower for Xabric. However, a baldra caretaker named REIMA is growing suspicious of her. [This sentence feels like a non-sequitur since we don't circle back to Reima again for two more paragraphs. You can add this sentence to the last paragraph, as something like, 'However, a baldra caretaker, who has been growing suspicious of her, catches her and Rider..." That'll save some space, improve narrative flow in this paragraph, and you won't have to add another named character] When K-1 learns that her best friend, K-TWELVE, [no need to name K-12 here. Just say 'her best friend.'] is being regularly abused by a Tower leader, she is stirred on a deep level, [I think you can omit 'stirred on a deep level' since it's non-specific, and go right to the action she takes] and makes a risky visit to Xabric only to witness Rider torturing him. Yet the following day, Rider steals her away to a romantic hidden spring, where Rider both proves he knows she is up to no good, yet also confides in her, showing that he’ll keep her secrets. She finds herself wanting to like him, and is overwhelmed by conflicting emotions. [I want a little more about Rider when he's first introduced. Is he handsome? Charming? Why is K-1 falling for him (despite his surprising geniality) when she knows he's torturing her friend? A little more character detail early on will make this shift in K-1's feelings seem genuine.] K-1 then learns that Xabric will be a sacrifice at Omniren. [again, here you can just say 'the upcoming holiday.'] Angry because he lied to her, K-1 abandons him. [What did Xabric lie about? Or was it Rider who lied? Specify.] That evening, however, K-12 [again, this can just be 'K-1's best friend'] accidentally creates fire, and K-1 recognizes it as the vague, evil power in her masters’ folklore. [How does she recognize it as such? Why does it make her so angry?] Her hatred of her masters and their lies overcomes her, and she rejoins Xabric, only to lose herself in the fog of Nen for days, [does she drug herself or is she drugged? If she's drugged, by whom?] emerging from her drugged state a day before Omniren. In the race to escape, K-1 discovers that Rider’s hitting her was a veiled attempt to help her. [How does this work? I'm sure it's not meant this way, but it reads a little like making an excuse for an abuser] Determined to understand his motivations, she ignores the danger and meets with him, and he kisses her. Having recently learned the baldra are homosexual, she now becomes distressed over her identity among them. [This is an odd detail. Wouldn't she have realized this earlier? If this sentence isn't vital to the plot (maybe K-1 is earlier questioning her identity because she's not attracted to women, or something similar) I'd omit it.] Reima catches her and Rider, and imprisons K-1, who escapes and frees K-12 from her abuser, learning in the moment that baldra are capable of healing. [There's a lot going on in this sentence. Suggest you break it up into 2-3 sentences] They are pursued deep into the Tower, where they find a machine filled with their blood and realize they have been harvested all their lives as a power source. [They knew they were being harvested, right, but they thought it was for scientific research? I'd bring this full circle if the fact that their blood is being harvesting as a power source instead is what's shocking to K-1]
When they reach Xabric, K-1 discovers he is a giant. [How did she not know this before?] He is too injured to move, and K-1 nearly gives in to despair, but her love of K-12 convinces her to fight an impossible battle rather than submit. [But she already rescued K-12, didn't she?] In the ultimate act of trust, she looks in Xabric’s eyes and allows him to fully control her. This act heals him with her power. Twelve then releases enough fire magic to melt Xabric’s chains, but Reima recaptures K-1 and is about to kill her when Rider saves her life. They part with K-1 believing he [Rider] is a friend, not an enemy. But before the baldra flee the Tower with Xabric, Twelve dies from overexertion. K-1 feels intense sorrow, self-blame, and loss of direction, but she still looks to the future as they escape. [Specify what 'looks to the future' means here. A life with Rider? Starting a new life with the baldra? It's the last sentence, so end with some enticing details.]
Overall, this is a good synopsis: it's well-written with a nice narrative flow. My main critiques are:
(1) Especially for a fantasy novel, where you've created new names for people, places, and objects, try to keep the proper names to a minimum in the synopsis. Otherwise, it gets very confusing for the reader, who likely hasn't read the whole manuscript yet and had a chance to learn all the names. For example, 'The Nen' can be the medicine, or the tonic, or something like that. 'Omniren' can be 'the holiday.' The only characters who seem to merit proper names in this synopsis are K-1, Rider, and Xabric (though if you can eliminate the proper names for the Nen and Omniren, then you can add the proper names for K-12 and Reima).
2) I included a number of how/why questions throughout. It doesn't take too many words to explain how or why things are happening. For example, in the last paragraph, you state that K-1 realizes Xabric is a giant, and that was confusing to me since it seemed like they'd met in the third paragraph. So changing that sentence to "Because K-1 had been near Xabric, but never actually seen him, when they reach Xabric's cell, she's surprised to discover he's a giant." That's a bit awkward, but it explains the situation and the reader doesn't have to pause to wonder about it. I tried to point out each place in the synopsis where I had similar questions.
Great job, and best of luck with this manuscript!