Irradiate is the one with the good def debuff of the AOEs (off the top of my head, around 36 or 37%).
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Irradiate is the one with the good def debuff of the AOEs (off the top of my head, around 36 or 37%).
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-37,5% defense for 10 secs apparently.
Neutron bomb -25% Defense to Target for 16 seconds
Storm/Rad might be better on paper (I don't know that for a fact, but I suspect it may be true), but I have a lot of fun with storm/psi. More of a concept build than anything else but a lot of fun.
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Go with Rad. Psi is good for the -recharge, but dmg wise it sucks. Rad is not much better dmg wise but the debuffing will be more handy for avs.
I recently ran some numbers and was shocked to find Psi rather heavily resisted (Well not resisted as such but very few have an actual weakness to it). I was shocked... ok not that shocked, but what I was shocked at was that Energy and N. Energy is quite likely the least resisted Damage type that a Defender has access to (Toxic is of course the least resisted of all by a long way but Pure N. Energy and Energy are not that far behind. Same goes for pure Fire or pure Cold Damage but pure Cold/Energy is hard to come across, most of the time it is coupled with smashing.)
So My bet would go with Rad as being the superior choice... Pure Energy Damage, a 10% ACC bonus as standard and reduces defence... making them even easier to hit 
i am currently running a storm/rad and it's just coming into its own little niech great fun in teams and av's dont last to long 
I have a Storm/Psy, and a /Rad for comparison. Both are in their 20s.
Without the shadow of a doubt, /Rad is the more rewarding set early on. Neutrino Bolt is an *excellent* power, the eye beams are good, Irradiate is a fantastic defbuff for the whole team, etc. The secondary effect is excellent - once you tag them, you won't miss after that. Energy damage is not often highly-resisted. It's a great set and hard to go wrong.
/Psy is a late-bloomer, and has several issues that make it harder to play well... some creatures have 90% resistance to it (the council robots mission with 2 x Storm/Psy was *long*), and it has inconsistent secondary effects that make it harder to fire-and-forget, and it has no coherent "1-2" attack (you can't just get by in single-target with the equivalent of Neutrino Bolt and X-Ray Beam).
That being said, extra range is fantastic if used well, the psionic snipe is very tasty, and having a mixture of secondary effects rewards competent play well - the mixture of recharge slow, immobilise, sleep, stun and knockback can really mess with single targets, and the recharge slow on Psychic Scream is *huge* - comboed with Snow Storm, it will floor recharge times on multiple enemies and thus massively decrease incoming damage.
You should also ask yourself whether you consider firing green "laser" beams out of your eyes to be cooler than froopy pinkish rings. Again, having played both, they both have their charm, but I know many players feel otherwise!
In essence though, it boils down to:-
Easy-to-play, fast, uncomplicated, low-maintenance set
vs
Slower, harder-to-play, complex set that rewards careful slotting and use
I find in team play I only really use iradiate and Cosmic burst from Rad, I can see 4 powers in psi that I would use when teamed, but none of them are as juicey as iradiate (but two of them are better damage than Cosmic I beleive. But not such nice status effect)
Rad is a good set for defending with, just from those two powers, but Psi is a much nicer set for blasting with (single target at least)
I think rad has the AoE edge just. Its a close thing
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They were appropriately appalled
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You just know energy blast beats psy and rad 
Howdy fellow heroes. I've been playing a Grav/Storm Troller for a while now (hes at L36) and I've became a big fan of Storm set. So I decided to make a Stormie defender. I'm trying to figure out which secondary to pick. I've thought of Rad Blast, so I could be a DefDebuff monster (Freezing Rain + Tornado + Rad attacks) or Psychic Blast for good debuffs and 3 disorient and 1 hold powers. Any opinions? Cheers.
*Edit*: Is anyone aware of the defdebuff numbers of Irradiate and Neutron Bomb and how long do they last? Thanks
@False Fiction - Virtue / Defiant
Current projects - [Glaciologist - Ill/Cold Troller] [Cloudshaper - Storm/Dark Def] [Harald Wartooth - Elec/Psi Domi]