Travon Baker made 1 of 2 free throws with 17 seconds left to put Northern Illinois up 67-65, and Chris Bond's shot with 3 seconds remaining missed as the Huskies (9-11, 3-5 Mid-American) held on. Armstead had a steal with 18 seconds left, setting up Baker's free throw attempts.
Baker tied the game at 60 on a 3-pointer with 9 seconds remaining in regulation, and Bond's runner at the buzzer missed.
Ball State (4-15, 1-7) led by 15 in the first half and 10 in the second half before the Huskies came back. Northern Illinois took its first lead since the game's opening minutes at 55-54 with under 4 minutes to go, setting up a tight finish.
Colorado State graduate transfer John Gillon has chosen Syracuse, giving the Orange a potential starter at point guard entering the 2016-17 season.
DeSean Murray, who averaged 20.2 points as a sophomore at Presbyterian, will transfer to Auburn to play for coach Bruce Pearl.
Former Kentucky guard Ed Davender, the only Wildcat with at least 1,500 points and 400 assists, has died. He was 49.