Casimir, a freshman, finished with 33 points on 11-for-17 shooting, while David Laury contributed 20 points, grabbed 11 rebounds and dished out six assists.
Iona (18-6, 11-2 Metro Atlantic) shot 57.9 percent on 57 attempts from the field, hitting 15 of 27 from long range, and never trailed in the game. Ryden Hines added 11 points to go with 13 rebounds, Kelvin Amayo had 10 points and A.J. English dished out 11 assists in the win, the fifth-straight for the Gaels.
Marist (5-19, 4-10) cut the deficit to 59-52 with a free throw from Khallid Hart midway through the second half before Casimir sank a 3-pointer at the end and Iona extended the double-figure advantage down the stretch.
Chavaughn Lewis led Marist with 24 points and Hart finished with 19.