Exciting beginning. I only have two complaints with this prologue. One, is that you started with weather, which isn't a great hook. I would start with Elise running through the swamplands, and afterwards bring up lightening to emphasize the setting.

The other crit I have is for the second paragraph, which is fairly infodumpy. This would read a lot better if you integrated that information into what Elise is doing rather than just explaining the problem of Chaos and the Swamp Crawlers instead of writing the information out like a history lesson of the swamp. Bring that information into her direct thoughts to keep up the pacing, instead of taking a break to explain where she is.

Wow! You have some real talent!

This has potential. But I noticed a few things:

"It was a dark and stormy night..." Seriously? This is almost as cliched as "Once upon a time..." You want to strongly consider changing this.

"She lunged herself towards dry land..." Take out "herself".

Another major problem was that the prose is a little choppy; the actions don't really flow together sometimes. Try to avoid starting every sentence with "she" or "the" - I saw a lot of those.

Just work on those things, because like I already said, this story has a lot of potential. Keep it up!