I don't know to much about either of those pwersets but I can say this: If you try to softcap ranged defense, you might cripple other aspects of your build. I would say defense to... something, some +hp, some recharge. +dam is nice but not as effective on a corr compared to some other ATs.
I'm not running a Dark/Cold but I've often toyed with the idea.
As for how to build it, here's what I'd do. Build for smashing/lethal defense with IOs, take the Scorpion Shield. With the Arctic Fog fix, its almost trivially easy to softcap s/l on a /Cold. After that, recharge, recovery and +hp to taste.
The only thing preventing me from making a Dark/Cold is the damage is a little low for my tastes and I've already got a Cold. Good luck with your rebuild 
Support Guides for all Corruptor secondaries and Fortunatas
The Melee Teaming Guide for Melee Mans
The Melee Teaming Guide for Melee Mans
At first I was fondly remembering how much fun she was in pvp, waaay back when. The I ran a few missions, and found her somewhat lacking compared to my other corrs. Got on a team, certainly pulled my weight enough, but still felt like a benchwarmer.
I'm not home or i'd put up a mids of her current build. But, I'm not really sure how to build her, one build for teams, one for solo. WHat do I look for, ranged defense/+damage? What about the Alpha slot?
Anyone running a dark/cold these days?
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