This is a set that looks kind of neat, but is a long and drawn out game versus the AI. No ground breaking story, just a chess match. Feel free to tear this a new one.
I made something similar a while back here. Only difference is that you have two Bishops. I think that having a Hydra as Knight makes more sense and looks better. And like you said there, this kind of thing looks pretty cool but the gameplay is absolutely terrible. I was never able to finish my scenario before I got really bored.
I've tried building a scenario like this too, and I've played a bunch of them in other people's custom scenarios. It seems like a great idea, but the battle is always dull. At least yours is pretty! It might be more fun if the player just controlled a regular sized party perhaps. Not sure.