The Mavericks' Tre'Shawn Thurman tied it at 101 in OT with a jumper, but Calder hit his 3 with 27 seconds left and Landis iced it with two free throws.
Trailing 50-37 at halftime, the Mavericks twice rallied to within a point before Jake White hit two free throws to tie it at 92 at the end of regulation.
Landis hit 9 of 12 3-pointers, tying his career best. John Konchar scored 27 points and grabbed 12 rebounds, and Brent Calhoun and Calder added 12 points apiece for the Mastadons (15-5, 4-1 Summit League).
White scored a career-high 26 points and grabbed 11 rebounds while Devin Patterson added 24 points for the Mavericks (12-7, 4-1). Tra-Deon Hollins scored 23 points with 13 assists and eight steals - both career highs. Thurman finished with 20.