Rendar's Wrath

ASK FANTASY FLIGHT 

Q: If my opponent declares a unit with Shielding as an attacker, does the effect on Rendar's Wrath happen before or after the shield is placed on the attacking unit?

A: Shielding is "When a unit with shielding is declared..." and Rendar's Wrath is "After an opponent..." The timing word 'when' comes before 'after,' so Shielding would happen first and thus your oppoent would be able to negate the damage from Rendar's Wrath with the shield.