Randomizer hell
Fortress hell
Perhaps 24/7 medieval mode
Aand The Hunted mode? (Basically like saxton hell, but everyone is going up against this ninja spy that cloaks for an infinite amount of time. He also has way less health than saxton I believe)
In certain cases it can be easy for the spy to win, but with a little teamwork the players can just camp in certain areas of the map.
Although this is a pretty rare mod, I've only played it a few times. In some cases you have to work to protect an engie with the intelligence while keeping the spy at bay until you reach the point.