MAYVILLE, N.D. — Jax Mattern remembers his last high school regular season game vividly. The Shanley quarterback accounted for nearly 90% of the Deacons offense in a 53-47 overtime loss to West Fargo Horace on Oct. 24. “That game was probably the most fun game I’ll ever be a part of playing football,” Mattern said. “That’s one of the best games probably in North Dakota high school football history. It was just two great offenses, great defenses …