Each of your units rolls attack dice secretly until end of game. Show them to your opponent after damage prevention.
Roll the attack dice without your opponent knowing what the result is until all effects have been applied. When the damage prevention POP (p.41) ends, reveal the die roll result. It is best simply to roll the dice after your opponent applies dice roll, pending damage, and prevention POP effects. Triggered effects (such as Fury) that are dependent upon what the dice show are only applied after you actually roll dice. The number of dice to reroll is chosen before knowing, but which dice to reroll are chosen after the dice are revealed.