NK-7 Ion Cannons Weapons Ugrade card
How-to use Ion Cannon "NK-7 Ion Cannons" - Star Wars Armada Explained (SWAE)
Instructions and hints by Karneck
Blue : Exhaust this card to force the defender to choose and discard 1 of its defense tokens.
This Upgrade Card must be exhausted and triggers during Attack Step 5: "Resolve Damage"