Critique: 'The Empty Ruins' by Death Dragon
It's not bad, but there are a few problems. Firstly, you tell more than you show. Almost every other line of dialogue your characters utter is done so 'angrilly' or 'formally' or 'unconcernedly' etc. Alec 'grows serious' instead of his expression or posture changing. This trend is most problematic in the main duel itself, not least because it serves as the climax of the story. In fact, I think it's probably the weakest part of the story which is without doubt the biggest problem.

Your duel simply doesn't work. First point, if a fight is lasting 'a few minutes' it is most emphatically not a short fight when both combatants are using lethal weapons. Furthermore drawing blood is understandably a very big deal, yet none of Alec's strikes are described at all and Derek's only get focus on his 'comeback' (which represents well under 10% of the actual fight in pure time, btw). You obviously can make at least a competent attempts at writing it, but you just chose not to. The first paragraph should contain much more detail. How does Alec take advantage of Derek's weakness? Does he parry or dodge? Does he let his armour take some hits? Are either of them even wearing armour? Are they driving each other back and forth? Circling? Where are these superficial cuts Alec lands? Why are they only superficial? Does Derek pay much attention to them and, if so, how does he react to them?

In a pivotal fight (which this is) most, if not all, of the above should be answered and you've not said anything about any of them. You obviously aren't incapable of describing strikes and blows so you really need to start doing it.

Beyond that, there aren't many other errors. Your dialogue is decent, although in places it seems a little unweildy. One minor complaint is when you describe the walls as being 'once-solid' as, unless they're now composed of magma, they are technically still solid. Consider words like 'sheltering', 'impenetrable', 'unbroken' and the like. Grammatically you're pretty good, although again you're a little heavy on the comma in places. If you fix anything though, re-write the fight.