Impressions while reading:
Your first paragraph rocks! Bravo! I am hooked, more than hooked, glued to the page.
Some grammar mistakes, but nothing that can't be cleaned up in post.
Er... the constables know the pods will only last thirty minutes, and yet they are playing catch with the monsters... are they retarded or just completely irresponsible? The catch scene is cool, and it can stay I guess, but you need to show the constables buckling down or something, realizing that the situation is more grim than they first supposed.
Dezkin crawled away from the twitching creature. "They're called thralls. Haldor raises soldiers from the dead and transforms them into those clawed things. They're fragile, but I don't think they can be killed. Their only purpose is to poison people with their bite .Those things with the horns on their snouts are called vorns."
Okay, this is a really long and detailed explanation for the middle of a battle. I would expect something more along the lines of "They're called thralls! They poison people!" At the very least, throw in a few exclamation points. Shouting is appropriate when attacked by the undead. You can quote me on that.
He stomped his foot and shook the ground, knocking Abby and Dezkin onto their backs. Suddenly the forest came alive with thralls and vorns.
This makes it sound like the monsters come from the forest, but then you say that he threw them back towards the town from where they came. It's not clear what's going on.
Boy was he wrong.
Okay, what does this mean?
Alright, here's my critique:
I loved your descriptions. I saw the battle in my head, and only a few minor things drew me out of the story as I noted above. The battle makes much more sense now, and I feel the emotion and the power of what's going on. Well done. Other than what I noted above, my one and only critique is this: it's too short. Well, not too short necessarily; I guess what I mean is that your ending isn't really an ending. It feels like there should be more to the chapter. There needs to be some sort of closure, or some sort of cliffhanger. Here, we have Will walking around a building looking for his dad, and that's it. It's a great chapter, it just needs finishing.
Again, very well done, a huge improvement over the first draft.