MajorDecoy

It wouldn't have to proc off of multiple targets on one swing, but imagine that they have successfully coded it so that the proc chance is dependent upon the recharge time.

Let's say that a power that recharges in 5 seconds, whether single target or AoE, has a 10% proc chance.

A single target power will have a 10% chance to go off every 5 seconds. An AoE power will have a 10% chance for each target it hits.

With three targets in range, there's a 27.1% chance you'll get at least one proc (correspondingly, a 71.9% chance of no proc).

1 2 3
n n n .9 x .9 x .9 = 72.9%
p n n .1 x .9 x .9 = 8.1%
n p n .9 x .1 x .9 = 8.1%
n n p .9 x .9 x .1 = 8.1%
p p n .1 x .1 x .9 = .9%
n p p .9 x .1 x .9 = .9%
p n p .1 x .9 x .1 = .9%
p p p .1 x .1 x .1 = .1%

So you'd have a 24.3% chance of one proc, a 2.7% chance of two procs, and a .1% chance of three procs. I would not be at all surprised if you hadn't noticed multiple procs from the same swing.

Now, there are arguments to be made that the bonuses should stack more, or that they should have a higher proc rate, or that the resistance bonus is too small, but that's a different argument.

If indeed, proc rate is a function of recharge time, then two attacks of identical recharge time should have identical proc rates, regardless of how many targets said attacks are hitting. That is the balance concern.

I suggest blaster

Mage Armor: This improves AC, so your options are Personal Force Field, Ice Armour, or the Black Scorpion's Patron Power Pool Shield.
Magic Missle: I use Long Range Missile
Fireball: Pyronic Judgement
Cone of Cold: Ionic Judgement
Some sort of summoning power: I like Summon Polar Lights, they feel like Lantern Archons.

I also grabbed Ionic Judgement to have Chain Lightning.

Disintegrate, however, is not a spell you get in any class.

Edit:

I suppose a Dominator could work too.

That's probably a bug and not a feature of the proc. From what I've heard, the brute proc is also granting about 5 extra fury per target hit, allowing Brutes to maintain 100% fury if it's in an AoE. We have to presume that's not working as intended and that they're likely to alter the procs such that they only have a chance to fire once per power activation rather than once per target hit.

Give it a try on test. It'd be a waste in the sense that it's proc/recharge, and you'd get little use out of the /recharge portion of it.

If it uses standard proc rules in toggles, it would have a chance to proc once every ten seconds, the 20 second duration of the buff would mean you'd never have more than 2 stacks.

However, there's nothing to indicate so far that these procs follow standard proc rules.

In jab it was up reliably one stack, but it seemed pretty lucky if I got it to double.

Stone Armour. I don't like having to turn off my status protection to be able to hop around.

Annoying?

Give them a very fast recharging, auto-hit, unresistable Siphon Speed.

I like the shirts.

We totally have it.

My Blaster who studied under Xagyg can cast Magic Missile, Cone of Cold, Chain Lightning, Fireball, Mass Haste, Summon Lantern Archon.

He's got meta-magic, he can extend spell to increase range, empower spell to increase damage, and a couple of ways to bypass spell resistance (piercing spell).