Grits blitzes.
8 man rushes the entire 1st qrtr and hit Allen on every single down.
If he's still standing in the 2nd qrtr keep running it but dropping the occasional zone dawg in there to see if you can steal a turnover.
Complement this with heavy packages on offense to run both the ball and the clock and with just enough PA sprinkled in to keep the 'backers honest.
If Allen finishes the game, you probably lose, but at least you have a punchers chance to break him.
Oh, and sacrifice goats in the locker room both pregame and at halftime.