i've managed to build a mavor in 5 minutesish against a supreme ai. If you can commit the resources to it it is a game winner. The cybran rapid fire artillery is also really nice though, not as good as the mavor but can still be a game winner, i mean its rapid fire area of effect, just dont try to hit anything with it, aim for the middle of the base.
What i find is, the mavor is unfairly accurate, your commander doesnt have a hope in the plafce where the devil lives...
I post more later, right now its lunch time
