I also made a post you can read more about it here: http://www.byond.com/forum/?post=2306089
And I leave you with this gif to give you a sneak peek of the combat:
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I am still working on it and polishing it everyday so please give it a try if you are able to. I've worked really hard on this and I am really looking forward to your feedback and criticism. Thank you!
I don't have much to say about the AI since Unwanted4Murder already covered it.
Regarding the fire ability you used on the mushrooms, I do think it should have slightly stunned / knocked back the enemy instead of letting them walk through it. The character animation made it seem like a heavy attack, so maybe adding screen shaking to it with the stun / knock back effect would give it a more powerful feel.
Edit: A follow up to my previous suggestion. Perhaps setting it so the move can be chargeable would give you multiple levels of how large of an area the fire covers and how intense the screen shake and stun / knock back effects are.