When does the Raider ability and Diala's foresight ability trigger? Is there a way to determine which order they are performed in? We had a bit of a standoff over this one last game.

Mission rules -> attacker ability -> defender ability

So

1. Weequay decides if he wants to force Diala to reroll

Yes -> Diala reroll, that die is now locked and cannot be rerolled by Diala's foresight or any other means

2. If not, Diala may use foresight to reroll. Again, that dice is now locked and Weequay cannot go back and use Raider anymore

OK great!

Oh and I forgot about the one reroll rule... so many rules (sigh)

The full story: Ability Resolution Order During Attacks

2 hours ago, ricope said:

2. If not, Diala may use foresight to reroll. Again, that dice is now locked and Weequay cannot go back and use Raider anymore

Foresight is a defender reroll ability, so the Weequay cannot go back to attacker reroll abilities (not even to reroll a different die).