The "Void" powerup would function as a dumbfire single shot, probably hitscan, with a charge time of about 1/4 of a second, if it hits the opponent's car, it fires off any powerups they have stored, simultaneously; making them 'void' their reserves.
You can make them waste that Raptor they're saving for the overtake, or Firestorm boost them into a ledge or outcrop.
If there are two identical powerups stored, one is simply dumped, as the other is fired off.
It could backfire, of course, you'd need to be in line with them to make it work, you could drop their Quaker into your face or something equally comedic.
Messing with opponents in this way could add an extra layer of strategy, players may avoid saving the firestorm for the straight as it could be activated for them while threading tunnels.
Just an idea, though, the implementation would need quite a bit of testing for it to work properly.