Before I get flamed, radiation is a good set. I am not against the set at all. It is a set, though, completely carried by a small handful of its early powers. I'd like to see something along the lines of the below as QoL.
Fallout: thematically exciting, but this power is in reality lackluster. On a Def, it does about the same dpa in your primary as Rain of Arrows in your secondary, but with a huge recharge and the severe gate of needing dead teammate. You may pop this off once in a blue moon, but if we're honest it just becomes a set mule. A cool option would be to allow it to be used on a living teammate if they have a debuff and purge that debuff (however it would make sense to implement). This would make it uniquely useful as well as still within its theme of flipping the tables.
Mutation: the same issue of most the rezzes that you do whatever you can to avoid using it. This has become worse over time with the ability for anyone to combine Inspirations to make awakens and with the vet reward rezzes and incarnate power rezzes. I'd love to see this changed to be like Nature Affinity's where you can use it on a live teammate for a chunky heal instead so it has dual purpose and more mileage.
EM Pulse: The special against robots is exciting until you see it happen and realize it is pretty minor; the -regen would be good but it's so short-lived and also completely eclipsed by lingering radiation. The -recovery on you feels unnecessarily punitive given the power turns out to be a long-recharge minion and lieutenant- level hold. I'd like to substantially up the damage against robots, remove the self-debuff, lower the recharge time and extend the -regen, but open to any other suggestion on this one.
Choking Cloud: I'm sure there are folks that like it. But the end cost is high for a trivial mag hold aura. Even on a Cont I think I'd rather just hope for containment than try to pay the end cost. Would love to slash the end or give it more effects to justify it.