The moment to moment writing isn't bad, but feels more like you're moreso telling what's happening instead of immersing us in the situation. Maybe you could increase the stakes- like, if this bombing mission doesn't work, bad things happen back home. Some simple tropes like that would give you a way to more eloquently "imply" the scenario than just having a character explain it to another. It might also help if you crank the suspense with some emotions like fear or blood-lust. Mountains, spiders, and bombs are all things that could play well into a horror perspective; or goblins and dwarves are pretty fun factions that might have fun dialog and rivalries to show off.

Keep at it, you've got really good inspiration, I would love to read more with some tighter story-telling fundamentals =)

A decent story, it was a fun little excursion. What I think would have really elevated your story would be being more descriptive. You left a lot of blank space that could have been filled with more descriptions to help us feel like we were down there with the dwarves. The middle of your story was the strongest when you did that, but unfortunately I felt the beginning and end just lacked that extra sauce. Also I would have had more consequences for the early explosion. It felt the plan still went off they just had a minor set back. I would have really liked to see them have to improvise due to a larger consequence. Over good, I enjoyed it