Really has lots of things it stops. Luke can't toss an enhancement to double strike. Leia still ends up captured but doesn't get her Interrupt. You have until the end of the engagement to play any event you want without any of the event cancel effects being usable. Less good, Nudj's can't bump the dial if they leave play and the Speeder Bike won't die if you win the edge battle.
Actually this gets back to an interesting question. Do you have to initiate the effect?