This is a great guide and really helpful. I wanted to make a Def Poison/Rad (primarily because I want a Rad Blast again and I thought this would be a good pairing). I'm not opposed to Fire, but wanted to see if I could get Rad to work as well. Alternately, I'd be interested in a Beam Rifle if I could get that to be effective as well.
I made a couple builds cribbed from your poison/fire build and from KnottEwe and Vea. If you have time, could you please look at these two ? I understand that both would probably underperform compared to Fire in terms of damage. I'm looking for some variety of powersets, though, and would settle for less damage overall as long as the build is still decent.
Also, do you think you could do a video of you fighting a pylon? Or maybe just describe your attack chain for an example of how to fight a GM/AV?
Defender - Poison/Rad/Mace
Defender - Poison/Beam Rifle/Mace