Salutations!
So I took a look at your prologue that you've got up and, as per what you wanted, I put together some feedback for you! (I hope it helps, writing can be such a lot of work!)
On the technical side of things: Your very first sentence as a space in the beginning just before the first word that isn't an indentation, just a space. I'd format that when you have the chance. In the first paragraph you have this:
"He whisper to his baby" change 'whisper' to 'whispered' and that should be good. Down towards the bottom of the page where Darcy is being spirited away by the sparrows, you have this sentence:
"Sparrows swarms them, making a veil of dark feathers." In this case, change 'swarms' to 'swarmed' and 'making' to 'made' (or use another word). Be sparing with -ing words in fast paced scenes because they weaken the narrative (same with -ly words in some cases. Try not to over use -ly). I'm not saying never use them, but -ed words make the action sound as though it's happening right then and there, -ing words slow down the pace. (You'll actually begin to notice this as you write, that -ed comes across as very 'in the now' during scenes.)
You have a few instances of words missing their -ed, -s, or losing a letter that a spellcheck wouldn't catch: "Jessica tilted her head, he auburn hair" Those ones are always stinkers to find and everybody has them, don't worry. Just read your sentences out loud to catch them. You've also used "lead" instead of "led" here: "Duncan scooped up the baby and Isolde lead him outside." In this case, you'd want to use 'led' for the direction instead of the metal.
Now, you also have instances where you reuse words in the same sentence and it weakens your sentence structure. This is an example: "Isolde whipped and whipped and whipped at him." This makes the action scene come off awkward and I can't really feel attachment to what's happening. We know she's whipping him because you've previously shown her doing it, so I'd suggest using a different action word. (Don't forget, you can use stuff that applies to swords! "Sliced", "cut", "swung", etc.) Always remember to check your sentences and paragraphs for words that are overused, it can make the narrative tired or feel repetitive and it's a very easy trap to fall into.
So that's just some technical feedback I have for you in regards to the writing structure. Here's for the more storied stuff:
I like your start, I felt Duncan's surroundings. You can instantly understand his bond with his daughter in the way she's described and you have a sense of Duncan that makes you feel bad about his oncoming fate. Here's a man who loves his baby, and her mother who he hopes to get back (and he hopes so much he can't recognize a lost cause). It's a moving place to begin and you can feel it right from the off, so great start there. Your description in the beginning of your prologue was more robust than when your action scene came into play. You do still moments very well, but the transition from still to action suffered.
This is okay! Action is hard to write, flat out. It just is! So, what I would recommend is trying to apply the same level of attention to detail (in terms of surroundings, what does the air feel like, is it suddenly hard to breathe, is he losing his footing, and is the ground wet or cold? Stuff that’s used as a way to embellish how bad of a battle Duncan is really having). It'll really help sell the moment. Also: Spell names. It slowed down the action for me to have them calling out the spell they used each time they used it. My mind started to wander and that's not a good place to put a reader. The best way to avoid this is to treat the reader like they've learned the spell too. (Haha everybody gets to level up together!)
For instance this: “Pestaura” Duncan shot a blue bolt at Isolde's eyes. She grabbed her face as he shot another, “Pestaura,” at her knee. -- It comes off awkward because it's more the narrator saying it than Duncan on the second go and it takes the reader out of the scene. (The 3rd person POV should be subtle enough that we don't notice it as we would a character) Since we know he just used Pestaura, all you'd really have to say is "and another" or something similar. Repeating the spell every time it's used or calling it out every time, slows the action down and puts the reader in a very DBZ state of mind. It's kind of distracting. That's not to say you can never use the spell name, far from it. Just don't use them repeatedly in a single sequence or it might gum up the scene.
Phew, okay, if you've managed to make it to the end of all this (because, holy crap it's a lot!) kudos to you! I hope this feedback helps you. I actually read your book the first time you posted it and I'm glad you've thrown in some backstory to start with, it's a nice touch and it shows that you're growing as a writer. I actually think you'll weave a great story because all the elements are there, and you put them there. Even if it's a lot of feedback, just know that, you really are off to a good start and I hope you keep writing. You've got talent and you've shown that you're willing to improve and that's awesome. Here's rooting for Darcy Sparrow!