Evans' 3-pointer with 5:16 left gave Fort Wayne (11-11, 4-5 Summit) the lead for good at 59-56 and Forbes extended it to 66-60, capping an 18-6 run with 3:01 left.
Omaha (8-13, 2-7) pulled within three with 3:25 left but had two turnovers in the final 1:31 while Fort Wayne made 7 of 8 free throws.
UNO led 29-27 at halftime and 54-48 with 9:24 left. The Mastodons took their first lead of the second half briefly at 56-54. Rostampour tied it back up but the Mavericks would get no closer.
Joe Edwards added 16 points and five steals for the Mastodons, who won their third straight.