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eXeCuToR, great story, it's captivating. Don't be offended if I point out some flaws? We'll skip the grammar, as it's a problem for almost everyone. But the style... There's no denying it's good, but "I," "my," "we," and "us" are repeated too often – a couple of times in one sentence – that's too much.
Another point is the repetition not only of pronouns but also of other parts of the sentence. For example, the first thing that stood out was: "However, I couldn't let it show – it would demoralize the troops on my flank, frozen in perfect formation. Although the hordes of demons rushing towards us could demoralize even Elrath himself."
In the second case, the word "demoralize" could be replaced with a synonym, such as "frighten," "make tremble with fear," etc.
Perhaps that's all... everything that immediately catches the eye. As all writers say, you need to work on the text and style.
But overall, I liked it. Especially the description of the battle. The problem with most authors is that the description of the battle is boring, and it's impossible to visualize it in your head. Reading your text, I saw the whole battle in detail.
Thank you for the enjoyable time :)