I am curious to know what their mechanic patent involves. As far as I am aware, game mechanics cannot be copyrighted, and certainly any attempt to patent the rolling of 6-sided dice, seems quite ludicrous.
The combat system in Spartacus is pretty innovative. I agree with you that they probably can't copyright it... but it would be pretty obvious if another company lifted the system and used it in their game. It goes a bit deeper than simply rolling D6s