I think it's very doable. Here's the situation.
They have a mobility advantage. They have overlapping, and sucky, energy fields, and they have the dragon.
The dragon, is, to my mind, the problem. The number of hit points aside, it does a lot of damage, doesn't heal and can maul us till the cows come home.
We need to pin it and kill it, while avoiding getting sandwiched by the dragon and the shamblers.
We need the defenders to hold off the salads (especially the electricity field guys), and everybody else needs to focus on the dragon.
The leaders, hopefully, will keep us alive; if they have to prioritize...
1. Keep themselves alive. Stay out of the fields. Cross heal.
2. Keep the defenders alive. Especially if they've managed to pin a stormrage down somewhere where it's not frying everyone. Defenders have the most hit points, the heals "do more" for them on a point by point basis.
That's my opinion of course, but killing the dragon is "the hump". It's not like this would be an easy fight with "just" the dragon.
[d]--[/d]
The fight is similar to KK1.
Difficult terrain (less of it, but the map is much larger)
One solo with mobility that can be in proximity but prefers range
Some annoying grunts that are close by
In KK1, people tended to say "I can't get to the solo on this turn, I'll just attack something nearby". I'm not sure that that's a winning strategy.
There are 8 of us. If 2-3 people can tie down the grunts (different people each round if necessary) that leaves 5 people, with all their dailies to deal with the solo.
Lock him down and take him out and the whole profile of the encounter changes.
[d]--[/d]
Just as a mental exercise...
What would you do if you were victim?
1. Ideal scenario would be to have the PCs tied up with the stormrages while the dragon hangs out at long range and cherry picks strikers/controllers. One on one it can probably down one character every round or two (I think, I'm not sure.... I deliberately haven't looked at any stats, the aboleth vs belkar was weird on a lot of levels)
2. Next best would be a divide and conquer type situation. It's a solo, it likes being near a couple (i.e. 2-3) PCs, while it's stormrages hold off the rest of the party (5-6)
We may not have an "optimal" strategy (unless someone can create a zone that supresses lightning effects) but we can act to deny the dragon (through victim) its optimal strategy > imho that's effectively our "optimal" strategy.
Personally I think that means mobbing it with PCs who're dumping dailies and action points; while holding off it's supercharged fodder. (He repeats himself)