Fire/Dark? Great AoE carnage + Tar Patch 
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Fire/Dark is not a bad suggestion 
I've tried Fire/Rad, Rad/Rad, and Ice/Dark, tho only up to lvl 20 or so, and I have to say of those I've enjoyed Ice/Dark the most...
Fire/Rad worked well for a while with Radiation Infection as a way of mitigating damage, but as soon as you come up against mixed range & close damage dealers it starts to break down.
I've found the key thing to solo'ing as a corruptor is having ways to keep distance without too much hassle, and Dark Miasma is perfect for that with Tar Patch and Fearsome Stare. And Air Superiority has been good for me - I don't like Hover but want Fly - as it gives you a chance to move back during the knock-down if they did get close.
Having some form of self-heal is important too, so that cuts down the choices of secondary a bit. And Freezing Ray from Ice complements the distance-keeping nicely... it's a toss-up between that and the extra damage from Fire.
It's not as easy to solo as a Mastermind, where you always have the option to summon a second batch of minions when things go bad, but it's a lot more controllable... Some bits can get quite challenging, like taking on an equal or +1 boss and leuit at the same time and trying to kite them around a tar patch around lvl 15 ;D
Thanks guys.
Phaer you've gone and thrown a spanner in my plans now by mentioning MM's. I complety overlooked that option for soloing have never tried an MM of any kind. MM's are a better option for soloing then?
The 3 Brutes i've tried have no problems at all on their own and i dislike the Stalker approach , have a Dominator which is not so hot soloing but great fun when teaming.
Might move over to the MM forum for a quick looksie.
I've done a Ninja/Dark MM to lvl 23, and I have to say it was very easy going solo'ing - easier than the corruptor... the henchmen function like a mini-team, which means you end up doing debuffing and healing in support of them, and the second-tier henchmen have little trouble tanking leuits or bosses... Then later the third-tier henchmen adds area damage and debuffs, it's very cool. I even solo'd a couple of equal lvl elite bosses pretty easily at lvl 10 - one at a time - you just have to keep the heals coming ;D
But: in order to get good damage output (especially from the ninja's) you really need to micro-manage their movement carefully... the powers they use to attack are keyed by range, and so you're constantly making sure the second-tiers stay in melee range, because their damage drops by about 2/3 when they're using missiles.
It doesn't matter so much up to about lvl 18, but after that it became a problem, and that's what in the end made me decide to try something else.
So if you do try a MM and don't want to be mouse-clicking like a caffeine-addict on speed, i'd advise against Ninja's )
/Dark is a great option if you want to be able to solo, whether you go for a Corruptor or an MM. It's a fun mix of powers, too. The AoE heal on it is fantastic for MMs - especially those with ranged pets who'll tend to stay close to the MM. As an added bonus, it's also a fantastic set to have when you're teaming, too!
I took out a few EBs solo on my Ice/Dark Corruptor, so Corruptors are certainly viable solo. More downtime and risk than an MM, though.
The choice of an ideal solo corruptor heavily depends on your level of sanity. If you´re just a normal guy looking for some solo fun, I would recommend /Rad or /Dark in that order. Both have quite some powers useful for a team or a single player.
If you are totally insane there is only one thing you can do: take kinetics. It´s utter madness and you will have to wait some time to really shine, but you will rock.
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Last weekend I soloed a Fire/Dark corruptor up to lvl 15 and so far this weekend I've soloed an AR/Rad corruptor up to 13. Based on these experiences I'd have to recommend /Dark as the better/safer powerset for a soloing corruptor (in the 1 - 15 level range anyway). Dark's heal is better (once you've put a few slots of accuracy in it), its low level debuff seems more effective at stopping you from getting hit and it's got tar patch which is a very handy slow and debuff.
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Actually, on the contrary, I find Ninjas/FF plus Aid Other to be the least headache to solo, if you're not a perfectionist. Sure, it won't be the maximum damage per second if they stay ranged, but, eh, they survive anyway. The defense bonus seems to stack nicely with the bubbles, so they start being pretty hard to hit even on DOs. Not ice tank class, but enough to survive pretty easily while AO is recharging.
The only "micro-managing" I do is telling the whole gang to attack the same enemy, because otherwise they're like a bad PUG, everyone attacking a different target and chasing them down a different hall. But from there I couldn't care less whether they stay ranged or charge in.
Robotics is also a pretty good choice, though the protectors' bubbles are less defense than the innate bonus the tier 2 and 3 ninjas get. On the plus side, though, they also have some resistance and bubble you too.
Hey, I'm certainly not knocking the Ninja's... as i said, they are very easy to solo with, as long as you look after them (and make sure they don't charge off to kill stuff when they run and then drag half the mish to you)... I've not played another MM above lvl 10, so I've not much basis for comparison 
But it sounds like you're doing what I did for the first 18 lvls or so... besides keeping the dps focussed, what annoyed me most was the tier-1's dashing in on Boss mobs as main melee and getting wiped, and making the whole fight a lot harder than it would have been if the tier-2 had tanked with the tier-1's doing secondary melee. It's especially annoying because the tier-2's ranged is so weak that he can't take aggro from tier-1's doing melee, and they don't move closer of their own accord. Once you notice that you end up spending so much time making it happen that you have little time to do other things... maybe that's just me tho.
I think Robotics is maybe just a bit easier to manage, because of the good and long ranged damage, and consequently them not chasing after mobs when they run. But the whole thing of summoning a second set of minions when the first get killed mid-combat is just such a great get-out-of-jail-free card, if you time it right it makes it very hard to die as a MM on solo mish's.
That's why I suggested FF to go with it. They _can_ tank an Elite Boss when properly bubbled and with Aid Other thrown in now and then. Plus, for all its pitiful damage, Force Bolt can keep almost anyone off their feet a lot of time, which helps with minion survivability too. Makes it a lot easier to play casually, and not worry much about making them apply any kind of tactics.
As for robots... well, what makes me really wonder is that, as I've said in the MM forum, from my experience robots and ninjas seem to act exactly the same. I'm told that one prefers ranged and one prefers melee, but that preference seems to have only a small-ish effect. Just like with Ninjas you see 1-2 Genin charging and the rest of the gang standing back and throwing shurriken, with robots you see... 1-2 tier 1 robots charging (why?) and the rest of the gang standing back and shooting.
*/rad is your best bet.
Hi Guys
Only Corruptor i've rolled is stuck in the mid 20's as a Thermal/Rad and not enjoying the experience so much. Seems more of a team orientated set and i hope to solo more.
Any suggestions as to a solid "Solo" combination for me to try?
Cheers
Edit: Should have said only for PvE play.