Looked up Doomguy. I have played Doom, but never knew him by that name. At intermediate, he would get owned.
It would be a very advanced tank, capable of 90 mph, which is not unreasonable given the modern Abrams can make 60 mph. The main gun, which would only be used in very long range shooting or fighting large opponents, would use rails to fire high explosive rounds or depleted uranium rounds. The coax and hatch mounted particle beams would do much of the heavy lifting against magic swordsmen.