On a serious note, why are you getting close enough to a Dreg to be hit anyway when Lightswitch is on and they all have one level over you? It's not a hard encounter, just takes patience and time, not literally, well literally just not the sniper rifle. The only thing you need to worry about hitting you is that one sword captain that comes out each minion wave. Make sure you focus on him, other captains and wire rifle vandals and it's easy.