potential warmachine scenario - WIP

I've been pondering this idea for a little while now, but I think it's best I get a little help. I was going to design a scenario to play and whip it out last minute, but I think getting some input from others will help me polish the edges a little bit. It will lose the surprise factor, but I'm not sure it will make a difference.

Keep in mind that this is really the first time I'm putting this onto [paper] and will likely need some overhauling and possibly play-testing before I (we) could call it a finished product. It is also my first attempt at designing a scenario. Enjoy!

Project Exterminate intended for 2 players
The basic idea is that there will be a number of models ("Marks") not involved in either army, possibly 15. One player will be tasked with exterminating 2/3 of these Marks, and the other player will be tasked with defending them. The twist is that the Marks have a mind of their own, not content to sit idly by and watch the carnage. They want to wander. I think each Mark will use the deviation template to move D6" at the beginning of each players turn, with the 1 pointing roughly in the direction that model last wandered.

The Marks, I believe, should be deployed closer to the defending player. Perhaps three clusters 6" ahead of the defending players deployment zone.

The Marks will have the following stats: Spd* Mat5 Rat5 Str5 Def13 Arm13

The game will end on a set number of turns, I think 5 or 6 should be enough time for the attacking team to work their magic. It may work as well to start rolling at the end of the fifth round to see if the game ends (IE: on 5th turn game ends on a roll of 5+, 6th - roll of 4+, 7th - roll of 3+ et cetera.)

I think perhaps the attacking player should have a larger army because they will have spend precious resources killing marks while the defending player tries to pick apart the attacker. Perhaps attacker 20 pts, defender 15 pts for example. Although I  had originally thought the players would roll at the beginning of the game to decide attacker/defender. Maybe both players will have to bring some extra points just in case they are the attacker.

I suppose that is all for now. I would like to hear any and all input as everything is open for modification.

As always, HAPPY GAMING!