Neutrino Bolt can be its own attack chain. 
I have a hold proc in it, and I manage to hold bosses with it on an irregular basis. Back when I made my FF/Rad Defender, I thought Neutrino Bolt was the more recommended of the two powers by guides and various discussions in these forums.
Goodbye may seem forever
Farewell is like the end
But in my heart's the memory
And there you'll always be
-- The Fox and the Hound
Neutrino by far :
2 Acc/Dam HO, 4 proc= ranged buzzsaw
Quote:
This. On a defender sticking a standard SO into Neutrino gives about 7 extra damage (33% boost, damage at 50 starts at 22), sticking a Proc in averages an extra 14 damage (20% chance of 70 damage at 50).|
Originally Posted by Mc Carbonara
Neutrino by far :
2 Acc/Dam HO, 4 proc= ranged buzzsaw |
So PROCs are much more effective in it, assuming you can live with the randomness.
You've a fair number to pick from, even outside of Purples : Devestation chance for Hold, Achilles Heel : Chance for -Resist, Touch of Lady Grey : Chance for Neg NRG Damage and Shield Breaker : Chance for Lethal Damage
You're looking at neutrino bolt-cosmic burst-neutrino bolt-repeat being your single target attack chain. Throw in electric fence before the repeat if you're using the electric APP.
Seems with Time/ you would be able to do that with quite a few of the tier 1 blasts.
Wouldn't mind trying it with a /Sonic. I'm getting a visual of a someone blowing smoke rings. 
Broke down and jury-rigged Mids to build myself a Time/Rad/Dark. It is looking to be a delicious little melee/debuff hybrid, on paper anyway.
However, it's hungry for slots like a little fiend. I'm trying to decide between actually using one of the first two attacks, in a chain for single targets involving Air Superiority and Cosmic Burst. It's kinda hard to tell them apart on paper, and I don't have a whole lot of experience with /Rad defenders, so I'm a bit curious what others think.
The build cranks out enough recharge that I shouldn't be stopping to wait on attacks regardless, and by the numbers, Bolt looks a tiny bit better on that front, plus it'd mean an extra one-slot wonder power I'd be able to grab, but I'm wondering if it's little plink damage wouldn't get frustrating.
Any thoughts?