Because you provided such comprehensive feedback to me, I'm going to attempt to give mine!
I'm genuinely sad I didn't get the chance to rate this in the allotted time, you deserve a much higher position. But I really enjoyed it overall. I'm always down for some havoc/chaos shenanigans.
I have a few points where I think your work needed a bit of improvement:
1) My main gripe isn't so much the technical side of it - as it's really good - it's more the broader story you're telling. In short, you're telling us too much. It's only up to 1000 words, it's important to tell a story that can fit within this limit (I struggle with this too). As you mentioned in a comment here, you struggled with the word count, and it does show. You're telling too big a story for the word limit (I'd love to see an expanded story of this, I love Blythe). In a lot of ways to my mind, you've spent a little too much time explaining the situation.
You'd probably still be able to tell the same story, with room to spare if you let the readers gleam from context with what's happening. You did alleviate this with the usage of breaks as they did help with the flow.
2) Speaking of the breaks, and while I liked them the second one was a bit wonky. To my mind we didn't need to know it was fifteen minutes later exactly, you already established the breaks are time jumps and I know they had half an hour until LZ pickup, but I still think the fifteen minutes was a redundant statement.
3) Onto redundancies, and odd phrases, which is my last point. Throughout the story, you have a few spots where you needed to just go through it again and tidy it up a bit.
You have really wonderful imagery in some points, like; "Grass and undergrowth burned away in small fires here and there. The air stank of oil and burnt flesh," really poetic and beautifully descriptive in a gross kind of way.
But then you have some odd choices, for instance; "Five of them, apparently elves, had teleported in," why say apparently? Seems a bit redundant. You could probably describe the elves that are coming in a bit more naturally. "Five of them stepped through a crackling portal that had materialised ahead of their lander. Elves. Surprisingly heavy..." Not saying what I wrote here is that great, but by removing the apparently, the reader is a bit more sure of what's happening.
Another one I can find right now is: "A line of purple fire slowly sliced down through the air in front of him, between the lander and his men." I actually like this bit, but it could just use a bit of work to really sell the awesome sight of the warp opening infront of him. Personally I'd say remove "in front of him" as the reader can already see that happening when you say between the lander and his men.
4) One final point, and that's still about odd phrasing, is the "Creepy stuff" line. I know it's his internal thoughts, but saying something in creepy, looses the creepiness. It could work if you were writing a satire, with more humour, but here it doesn't fit. You could say something like "I need to get out" whilst formulaic, it doesn't sound as cheesy.
All in all though, I actually really enjoyed this story. My critiques were very specific, and more related to stylistic choices than anything and that's heavily subjective. I loved the ending with the Havoc marines, talk about something not going according to plan, what a sight.
There's a larger story in here, that I hope you don't abandon, give it another 4000 words or so, and you'd have a brilliant short story. The opening segment I absolutely loved. It was like I ripped a page out of Aaron Dembski-Bowden's books, it read so bloody well.
A really great read, I look forward to seeing you in the next writing Jam, and I'll make sure to get to your story before the deadline this time!