I am a little out of practice in making a good build, but I can offer my advice.
You want Aim (or whatever the rad equivilent is) to go with buildup. I would use build up aim irradiate haze to obliterate everything around you. Cosmic burst is great damage and reliable stun; hard to beat that. Hasten would be great for getting powers like irradiate and cosmic burst to fire off more quickly. I would want total focus; not sure bonesmasher is needed. I would want stamina, but you could possibly rely on conserve power. I usually do not want both. Attack chains? Well, the quick blast, eyebeam, and cosmic should be just fine, and I would want hasten to speed it up. For aoe, I would use irradiate and explosive blast at high level, but at low level I think you must use haze with irradiate.
(I hate cones but sometimes you have to use them)
Just my two cents.
Get the first two attacks; good advice for any Blaster primary because you can fire the first two while mezzed these days.
You may want to pick up Power Boost; it boosts both the stuns and the defense debuff from Rad/. And if you get Aid Self that as well.
Arc #40529 : The Furies of the Earth
I have heard that Rad/NRG is a good combo. I have played it up to lvl 14 and have liked it so far (it is the only thing that has been able to pull me away from my scrappers lately). What is some general advise you guys can give me. What powers should I get ASAP, what can I skip, good attack chains, etc. Thanks in advance.