Dark/Dark or Robot/Dark?

I'd like some opinions here. I've never liked Dark Blast or Dark Miasma, mostly because the look didn't appeal to me. That's changed with power customization, and I have a great idea for a character concept now. But I'm unfamiliar with Dark Miasma and can't decide whether I want to make my new villain a corruptor or a mastermind.

Obviously the mastermind would be more "uber" (I've taken robots to 50 before, so I know all about that), but what would the corruptor be like? The attack chain on Dark Blast interests me, Tenebrous Tentacles and Night Fall look like they make for very rapid AoE damage with some recharge reduction.

And because it's relevant, this character would always be teamed with a claws/willpower brute. So, it's a duo character.

Your thoughts everyone?

Bots/Dark is pretty darn fun. I've tried alot of MM combos, especially when the comm officer farms would let you blast a toon to 32 to really try out alot of features. Bots/Dark is still my fave. It's a total lawnmower.