Long story short, we have a player that's about obtain the capacity to get about 8 proficiency dice when they aim a blaster rifle. And with their weapon + talents, they basically get enough crit and/or damage to decimate opponents on turn 1. And, they can reliably repeat this on each turn. The main trouble is this is character is so lethal that NPCs who can challenge them are basically going to murder the other characters that are nowhere near that kind of offensive output.
So, what ideas do you have to challenge this kind of offensive nuke?