Whenever Riot's Starfighter attacks, your opponent may discard the top 2 cards from his or her deck. If he or she does, the attack ends.| Pay 2 Force Riot's Starfighter gets Double Strike until end of turn.
Keywords
Double Strike
Double Strike: An isolated, static ability played after the attack end POP that means, "You may choose a unit that this unit can attack. This unit attacks that unit. Play only if this unit just attacked and only if it tapped for that attack." The unit must tap for the first attack, not the second. If it untaps, it may double strike again. Double Strike doesn't allow you to attack your own units.
Riposte
Riposte X: A cumulative ability triggered by the roll of a natural two during an attack that means, "If the attacking unit rolled at least one natural two against this unit, this unit does X damage to it when the attack ends." Only one natural "2" is counted from the attack roll after re-rolls. Negative Accuracy can't decrease the die roll to a natural "2". However, you or your opponent may use an effect to re-roll dice to affect the number of natural twos. (You only count the 2, if any, from the roll used for the attack.) Riposte applies only to dice rolled for an attack, not to dice rolls for abilities like Retaliate.