On my Dark/Pain corruptor I took Dark Blast and Gloom as ST attacks but skipped Life Drain because it hits like Dark Blast and if I really want to heal myself, I rather count on Nullify Pain (and Soothing Aura when I solo: it looks pretty and, with all the tohit debuffs I'm throwing at foes, I generally don't have to worry about my green bar).
Tenebrous Tentacles and Night Fall are my AoE, along with Soul Drain from the Dark Mastery APP. Solo, I use Dark Pit to neuter minions before using my cones, and (stacked with it) Oppressive Gloom disorients the lts who would like to melee me. When I'm in a team, even when I don't have to worry that much about aggro, I like to use Dark Pit before entering melee to give an Anguishing Cry (immediately followed by Soul Drain, they're both PBAoE on the same timer if you choose the Dark Mastery one, and sometimes it's nice to see a few big numbers instead of clouds of tiny ones, especially when Soul Drain scourges *.*). Even if it's not as effective as a controller/dominator's stun, it's still nice to immediately neuter annoying minions like Sappers, and help to your team's survivability.
Sometimes, when I get a saturated Soul Drain I would like to nuke soooo much, but after a few seconds I realize that getting short on end when people are counting on me to keep them alive isn't that smart. Blackstar's damage isn't really impressive anyway, so I skipped it (and since I20 we can get a sort of nuke with Judgement).
I also thought that Torrent would help me to stay alive when I solo but its loooong range was often counterproductive.
I primarily took Dark Mastery for the self rez (because it's frustrating to be able to rez others and not oneself) but I was pleased to see that Oppressive Gloom and Soul Drain synergize nicely with some of my previous powers 
Sometimes I miss a ST hold to mez some foes before they mez me, but I assume you can't have it all. Moonbeam still helps me to kill them faster.
I tried to build for defence but: if I get punched (and would need protection), it's often when I enter melee for Anguishing Cry/Soul Drain, the rest of the time I stay away from it to use my cones. I thought that S/L defense wouldn't help that much, and ranged defense bonuses often come with the 6th slot, which would have made me underslot several critical powers. So I use my tohit debuffs, my controls (immobs and stuns), my resists (Dark Embrace + World of Pain) and my heals to stay alive, along with careful aggro management, stealth, flight, and damage obviously ^^
Don't forget about Dark Pit, this is the reason dark has no big third attack and it offers a lot to a team. The bad thing it takes a ton of slotting to be useful and is only a mag 2 stun so will only take out minions, but its a ranged aoe stun.
Teneberous tentacles will be your bread and butter attack, an aoe immobilize with a 7.5%tohitdebuff this really magnifies any defense you do have. Someone commented that the tohitdebuff percentage is approximately equal to the same number in defense against even con minions. So slotting it for the debuff looks like exactly what you want to do.
Also torrent might provide some mitigation and an additional source of aoe debuff but it is very narrow. I find that with two attacks hitting and about 20%defense (I am dark/traps so you will be dependant on IO's) I become pretty close to unhittable. Very nice on a ranged toon as it dodges most mezzes this way too. Myself I like the TT/Nightfall combo but it might attract too much aggro for you. The annoying part is how the two cones are different sizes, TT is wide (really wide) and short, Nightfall and torrent are narrow and deep.
Don't overlook the procs you can put in TT as well, I have mine loaded up with three damage procs and it is by far my most damaging power (I highly recommend this). Another proc I have not tried but is available (I think through the tohitdebuff IO's) is a stun proc. With this proc in TT and Darkpit you might be able to stun Lt's fairly regularly while still getting a large debuff on them.
The procs you can put in the dark blast powers are pretty varied, I have not really looked at them for anything other than damage, you might find some real gems in here.
Consider for a moment: Torrent + Tents + Dark pit & oppressive gloom + anguishing cry + soul drain. Blackstar will be poppin off for like 700 pts of damage and everything you hit will be either faceplanted or stunned and debuffed like crazy.
here's some randomness for ya.
btw, if you go defense, yer gonna have to give up alot.
Villain Plan by Mids' Villain Designer 1.942
http://www.cohplanner.com/
Click this DataLink to open the build!
Random: Level 50 Magic Corruptor
Primary Power Set: Dark Blast
Secondary Power Set: Pain Domination
Power Pool: Speed
Power Pool: Leaping
Power Pool: Leadership
Ancillary Pool: Dark Mastery
Villain Profile:
Level 1: Dark Blast -- Dev'n-Acc/Dmg(A), Dev'n-Acc/Dmg/Rchg(5), Dev'n-Acc/Dmg/EndRdx/Rchg(5), DarkWD-ToHitDeb(7), DarkWD-ToHitdeb/Rchg/EndRdx(7), HO:Centri(45)
Level 1: Nullify Pain -- Dct'dW-Rchg(A), Dct'dW-EndRdx/Rchg(9), Dct'dW-Heal/Rchg(9), Dct'dW-Heal/EndRdx/Rchg(11), Dct'dW-Heal(11)
Level 2: Gloom -- Dev'n-Acc/Dmg(A), Dev'n-Acc/Dmg/EndRdx/Rchg(13), Dev'n-Acc/Dmg/Rchg(13), DarkWD-ToHitDeb(15), DarkWD-ToHitDeb/Rchg(15), HO:Centri(46)
Level 4: Soothe -- Dct'dW-Heal/Rchg(A), Dct'dW-EndRdx/Rchg(40), Dct'dW-Heal/EndRdx/Rchg(43), Dct'dW-Heal(46), Dct'dW-Rchg(46)
Level 6: Share Pain -- Numna-Heal(A), Numna-Heal/Rchg(43), Numna-Heal/EndRdx/Rchg(43)
Level 8: Dark Pit -- Stpfy-Acc/Rchg(A), Stpfy-EndRdx/Stun(17), Stpfy-Acc/EndRdx(17), Stpfy-Stun/Rng(19), Stpfy-Acc/Stun/Rchg(19), RechRdx-I(42)
Level 10: Tenebrous Tentacles -- GravAnch-Hold%(A), GravAnch-Acc/Rchg(21), Ragnrk-Dmg(29), Ragnrk-Acc/Rchg(29), HO:Membr(40), HO:Centri(40)
Level 12: Conduit of Pain -- EndRdx-I(A)
Level 14: Night Fall -- Posi-Acc/Dmg(A), Posi-Dmg/EndRdx(34), Posi-Dmg/Rchg(37), Posi-Dmg/Rng(37), Posi-Acc/Dmg/EndRdx(37)
Level 16: Enforced Morale -- RechRdx-I(A)
Level 18: Super Speed -- EndRdx-I(A), EndRdx-I(39)
Level 20: Hasten -- RechRdx-I(A), RechRdx-I(21)
Level 22: Soothing Aura -- Dct'dW-Heal/EndRdx(A), Dct'dW-EndRdx/Rchg(23), Dct'dW-Heal/Rchg(23), Dct'dW-Heal(27), Dct'dW-Heal/EndRdx/Rchg(27)
Level 24: Combat Jumping -- LkGmblr-Rchg+(A), Ksmt-ToHit+(25)
Level 26: Super Jump -- Zephyr-ResKB(A)
Level 28: Acrobatics -- Empty(A)
Level 30: World of Pain -- AdjTgt-ToHit(A), AdjTgt-ToHit/Rchg(31), AdjTgt-ToHit/EndRdx/Rchg(31), AdjTgt-EndRdx/Rchg(31), AdjTgt-Rchg(34), S'fstPrt-ResDam/Def+(34)
Level 32: Maneuvers -- LkGmblr-Rchg+(A), LkGmblr-Def/EndRdx(33), LkGmblr-EndRdx/Rchg(33), LkGmblr-Def/EndRdx/Rchg(33)
Level 35: Anguishing Cry -- LdyGrey-DefDeb/Rchg(A), LdyGrey-Rchg/EndRdx(36), AnWeak-Acc/Rchg(36), AnWeak-Acc/Rchg/EndRdx(36)
Level 38: Tactics -- GSFC-ToHit/Rchg(A), GSFC-Rchg/EndRdx(39), GSFC-ToHit/Rchg/EndRdx(39)
Level 41: Painbringer -- P'Shift-EndMod/Rchg(A), P'Shift-Acc/Rchg(42), P'Shift-EndMod/Acc/Rchg(42)
Level 44: Dark Consumption -- Erad-Acc/Rchg(A), Erad-Dmg/Rchg(45), Erad-Acc/Dmg/Rchg(45), Erad-Acc/Dmg/EndRdx/Rchg(48)
Level 47: Dark Embrace -- TtmC'tng-ResDam/EndRdx(A), TtmC'tng-ResDam(48), TtmC'tng-ResDam/EndRdx/Rchg(48)
Level 49: Soul Drain -- Erad-Acc/Rchg(A), Erad-Dmg/Rchg(50), Erad-Acc/Dmg/Rchg(50), Erad-Acc/Dmg/EndRdx/Rchg(50)
Level 0: Born In Battle
Level 0: High Pain Threshold
Level 0: Invader
------------
Level 1: Brawl -- Empty(A)
Level 1: Scourge
Level 1: Sprint -- ULeap-Stlth(A)
Level 2: Rest -- Empty(A)
Level 4: Ninja Run
Level 2: Swift -- Empty(A)
Level 2: Health -- Mrcl-Rcvry+(A)
Level 2: Hurdle -- Empty(A)
Level 2: Stamina -- P'Shift-EndMod(A), P'Shift-EndMod/Rchg(3), P'Shift-EndMod/Acc(3)
perma jump is ---> /up 1
I've thought about starting to work with archtypes I know nothing about, Basicly Im looking to Softcap or ..at least make this guy able to survive some hits, pain is my healing/support not making for pvp just pve tf based etc. Uh, Epic have not though about that yet, dark have no idea what powers I want but I got a few Ideas:
Darkblast
Gloom
Tentical Power
Life Drain
I want to keep powers about 4-5 max for team protection reasons, if you can come up with ideas that might help let me know or post a build, and I could work from that to find some starting ground.