Context: Cops are trying to get a view on an offender, there is a sniper out there trying to see the offender that is inside the high rise building.
A: Hailey (the sniper), I need you to get set for a high diversion shot at the ceiling. No joy, repeat, no joy, on my order.
B: Copy.
Sources: Feelings Chapter 13, a Chicago PD fanfic | FanFiction
Chicago P.D. S7E4 Script
What does A mean by "a high diversion shot at the ceiling"?