North Dakota State (15-1) lost a nine-point lead in the fourth quarter, but answered quickly after falling behind. RJ Urzendowski had catches of 32 and 33 yards to get the Bison in scoring range, and Wentz broke a tackle around the five-yard line and eased into the end zone for the lead with 37 seconds left.
Roberson threw three touchdown passes, but also an interception to Jalen Battle in the final seconds trying to get the Redbirds (13-2) in field goal range.
Wentz led a rally that added a title a year after predecessor Brock Jensen set an FCS record for quarterbacks with 48 victories.
North Dakota safety Christian Dudzik had five tackles in his 61st start, believed to be a first for a Division I player, to highlight a senior class that had more national titles (four) than losses (58-3 record). Appalachian State is the only other FCS team to win three straight titles.
Wentz, already the school record-holder for yards passing in a season, threw for 237 yards and a touchdown and had 87 yards rushing.
Roberson, an Indiana transfer, had 161 yards rushing and 157 passing, while Coprich added 106 yards on the ground.
Adam Keller had three field goals for North Dakota State, breaking the FCS single-season record for kickers with 145 points before his final point-after attempt was blocked to give the Redbirds a chance to win with a field goal.
The 6-foot-6 Williams expected to compete for the Hurricanes' starting job this year, instead tearing a knee ligament in the spring. While he got himself ready to play in September yet spent the season on the sideline behind Miami's Brad Kaaya.
Still, Williams was invited to the game for NFL prospects and took full advantage of his opportunity. Williams, who was voted the National team's MVP, had a perfectly thrown, 11-yard fade pass to South Carolina's Damiere Byrd in the third quarter that put the National team ahead for good.
The National team also got four field goals from Air Force kicker Will Conant and a 52-yard interception return TD from South Carolina safety Brison Williams — meaning both Gamecocks invited to the game left with touchdowns.