Deflective Plating is a "may" option. At what point do I make that decision?

Basically do I call it before rolling damage dice, or do I commit to it before rolling dice. Obviously I don't want to risk losing it if I roll zero damage anyway, but wasn't sure if that was the correct timing.

Thanks!

You may choose to not suffer the effect. You may not choose to suffer only part of the effect. So if a bomb instructs you to roll dice, the effect includes rolling dice. So you either skipp all of the effect or none of it.

In short, no you can not roll the dice for the bomb and then decide to not suffer what you roll.

The timing for it is when a friendly bomb detonates but before any dice are rolled. That's when you must make the choice to trigger Deflective Plating or not.