Dark/Energy is my only 50 Tanker.
Energy Melee is pretty much regarded bottom of the heap, because it has one very average AoE in Whirling Hands. It has good single target damage, but not really enough to make up, especially if you're farming.
Dark Armor is a great fit though. A damage aura helps out with the lack of AoE, and Oppressive Gloom lets you stun bosses in one hit. So get that power at 26! It has a way lower end cost than Cloak of Fear does, due to the very small self damage, which is pretty much irrelevant due to the powerful heal in Dark Regeneration.
I'd make that swap, and maybe ditch Conserve Power or Physical Perfection. You seem to be overdosing on end management toolos here. Dark has a rep for being an end hog due to two factors:
Cloak of Fear and the damage aura both chew up large amounts of end. Ditch Cloak of Fear.
Dark regen takes 1/3 of an end bar at base. The Touch of Nictus proc fixes that. With these two steps (and the Performance Shifter proc in Stamina) you can probably lose Conserve Power and Physical Perfection.
I'd look into an epic pool that gives you a bit more AoE damage, or at least take Energy Torrent. Maybe drop Manouvers? It's pretty marginal on a tanker.
Ahhh, - you've switched epic pool. I'd maybe go Fire and take Fireball for better AoE Damage. Ice Storm has a 2 minute recharge.
Oh yeah, Dark/Energy looks great by the way 
Moved things around but can't seem to fit in Oppressive Gloom and/or Pyre Mastery while also keeping max defense for Smash/Lethal/Energy/Negative.
Hero Plan by Mids' Hero Designer 1.707
http://www.cohplanner.com/
Click this DataLink to open the build!
Holly Hardon Collider: Level 50 Magic Tanker
Primary Power Set: Dark Armor
Secondary Power Set: Energy Melee
Power Pool: Fitness
Power Pool: Leadership
Power Pool: Leaping
Power Pool: Fighting
Ancillary Pool: Arctic Mastery
Hero Profile:
Level 1: Dark Embrace -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(13), RctvArm-ResDam/EndRdx/Rchg(15), RctvArm-ResDam(37)
Level 1: Barrage -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx/Rchg(3), KntkC'bat-Dmg/EndRdx(3), KntkC'bat-Dmg/Rchg(7)
Level 2: Murky Cloud -- RctvArm-ResDam(A), RctvArm-ResDam/EndRdx(39), RctvArm-ResDam/EndRdx/Rchg(39), RctvArm-EndRdx/Rchg(46)
Level 4: Bone Smasher -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(5), KntkC'bat-Dmg/Rchg(5), KntkC'bat-Dmg/EndRdx/Rchg(7)
Level 6: Obsidian Shield -- S'fstPrt-ResDam/Def+(A), S'fstPrt-ResKB(29)
Level 8: Dark Regeneration -- Theft-+End%(A), Numna-Heal(9), Numna-Heal/EndRdx/Rchg(9), Numna-Heal/Rchg(11), Theft-Heal(11), Nictus-%Dam(48)
Level 10: Swift -- Run-I(A)
Level 12: Cloak of Darkness -- LkGmblr-Rchg+(A), LkGmblr-Def(13), LkGmblr-Def/EndRdx/Rchg(17), LkGmblr-Def/EndRdx(33)
Level 14: Health -- Numna-Regen/Rcvry+(A), Mrcl-Rcvry+(15), RgnTis-Regen+(17)
Level 16: Whirling Hands -- Oblit-Dmg(A), Oblit-Acc/Rchg(19), Oblit-Dmg/Rchg(19), Oblit-Acc/Dmg/Rchg(23), Oblit-Acc/Dmg/EndRdx/Rchg(23), Oblit-%Dam(27)
Level 18: Taunt -- Mocking-Taunt(A), Mocking-Taunt/Rchg(27), Mocking-Taunt/Rchg/Rng(29), Mocking-Acc/Rchg(31)
Level 20: Maneuvers -- LkGmblr-Rchg+(A), LkGmblr-Def(21), LkGmblr-Def/EndRdx(21), LkGmblr-Def/EndRdx/Rchg(45)
Level 22: Stamina -- P'Shift-End%(A), P'Shift-EndMod(34), P'Shift-EndMod/Acc(34), P'Shift-EndMod/Rchg(34)
Level 24: Combat Jumping -- LkGmblr-Rchg+(A), LkGmblr-Def(25), LkGmblr-Def/EndRdx(25)
Level 26: Boxing -- RzDz-Acc/EndRdx(A)
Level 28: Tough -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/EndRdx/Rchg(31), RctvArm-ResDam(31), RctvArm-EndRdx(39)
Level 30: Death Shroud -- C'ngBlow-Acc/Dmg(A), Erad-Acc/Dmg/EndRdx/Rchg(37), Erad-Dmg(37), C'ngBlow-Acc/Rchg(43), Erad-%Dam(43), C'ngBlow-Dmg/EndRdx(43)
Level 32: Weave -- LkGmblr-Rchg+(A), LkGmblr-Def(33), LkGmblr-Def/EndRdx(33)
Level 35: Energy Transfer -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(36), KntkC'bat-Dmg/Rchg(36), KntkC'bat-Dmg/EndRdx/Rchg(36)
Level 38: Total Focus -- P'ngS'Fest-Acc/Dmg(A), P'ngS'Fest-Dmg/EndRdx(40), P'ngS'Fest-Dmg/Rchg(40), Mako-Acc/Dmg/EndRdx/Rchg(40), Mako-Acc/Dmg(45)
Level 41: Chilblain -- Thundr-Acc/Dmg(A), Thundr-Acc/Dmg/EndRdx(42), Thundr-Dmg/Rchg(42), Thundr-Acc/Dmg/Rchg(42), Thundr-Dmg/EndRdx(45), Thundr-Dmg/EndRdx/Rchg(46)
Level 44: Block of Ice -- BasGaze-Acc/EndRdx/Rchg/Hold(A), BasGaze-EndRdx/Rchg/Hold(46)
Level 47: Ice Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(48), Thundr-Dmg/Rchg(48), Thundr-Acc/Dmg/EndRdx(50), Thundr-Dmg/EndRdx/Rchg(50), Thundr-Acc/Dmg/Rchg(50)
Level 49: Soul Transfer -- RechRdx-I(A)
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Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Gauntlet
Level 6: Ninja Run
My suggestion would be to go Pyre Mastery this way:
Keep Thunderstrike sets in Fire Blast and Char and take FireBall. You can probably frankenslot this 2 Acc/Dam, 2 Dam/Rech, so we need two more slotsm, since Block of Ice only had 2.
Drop Cloak of Fear and take Oppressive Gloom. You do loose 3.75% S/L Defence, but, you have 70% S/L resist, a full heal every 20 seconds or so and a mez aura. And the ability to stun bosses with one hit. So do you really need that S/L defence?
OG needs very few slots so you can move them to Fireball. Is S/L Defence is a key goal, then no worries, I guess you dont need OG anyway.
E/N defence, on the other hand, is always good to cover your low energy resistance.
Oh yeah, for slotting Dark Regen, I'd change that Theft +Heal into a +Heal/Rech at least. The heal from Dark regn doesn't need as much slotting as Recharge does, since it will heal you to full from 3 minions unslotted. If you're farming, it will almost always over-heal you. You cna even skimp on accuracy slotting if you expect to face big groups all the time.
(Updated Build, Max S/L/E/N)
After having played numerous Scrappers and finding a "home" with the soon to be nerfed Shield set, I am taking a swing at a Dark/Energy tanker.
I am aware this combo might be more challenging then some, but that's part of the fun and fits well for the concept. If anyone can give some advice on build improvements I would greatly appreciate it.
The vision is to have a tanker who can group and mostly solo/farm. Glad's +3 def IO is not included due to being way too expensive on an already costly build.
Hero Plan by Mids' Hero Designer 1.707
http://www.cohplanner.com/
Click this DataLink to open the build!
Holly Hardon Collider: Level 50 Magic Tanker
Primary Power Set: Dark Armor
Secondary Power Set: Energy Melee
Power Pool: Fitness
Power Pool: Leadership
Power Pool: Leaping
Power Pool: Fighting
Ancillary Pool: Arctic Mastery
Hero Profile:
Level 1: Dark Embrace -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(13), RctvArm-ResDam/EndRdx/Rchg(15), RctvArm-ResDam(37)
Level 1: Barrage -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx/Rchg(3), KntkC'bat-Dmg/EndRdx(3), KntkC'bat-Dmg/Rchg(7)
Level 2: Murky Cloud -- RctvArm-ResDam(A), RctvArm-ResDam/EndRdx(39), RctvArm-ResDam/EndRdx/Rchg(39), RctvArm-EndRdx/Rchg(46)
Level 4: Bone Smasher -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(5), KntkC'bat-Dmg/Rchg(5), KntkC'bat-Dmg/EndRdx/Rchg(7)
Level 6: Obsidian Shield -- S'fstPrt-ResDam/Def+(A), S'fstPrt-ResKB(29)
Level 8: Dark Regeneration -- Theft-+End%(A), Numna-Heal(9), Numna-Heal/EndRdx/Rchg(9), Numna-Heal/Rchg(11), Theft-Heal(11), Nictus-%Dam(48)
Level 10: Swift -- Run-I(A)
Level 12: Cloak of Darkness -- LkGmblr-Rchg+(A), LkGmblr-Def(13), LkGmblr-Def/EndRdx/Rchg(17), LkGmblr-Def/EndRdx(33)
Level 14: Health -- Numna-Regen/Rcvry+(A), Mrcl-Rcvry+(15), RgnTis-Regen+(17)
Level 16: Whirling Hands -- Oblit-Dmg(A), Oblit-Acc/Rchg(19), Oblit-Dmg/Rchg(19), Oblit-Acc/Dmg/Rchg(23), Oblit-Acc/Dmg/EndRdx/Rchg(23), Oblit-%Dam(27)
Level 18: Cloak of Fear -- SipInsght-Acc/Rchg(A), SipInsght-Acc/ToHitDeb(27), SipInsght-%ToHit(29), SipInsght-ToHitDeb/EndRdx/Rchg(31), SipInsght-Acc/EndRdx/Rchg(31)
Level 20: Maneuvers -- LkGmblr-Rchg+(A), LkGmblr-Def(21), LkGmblr-Def/EndRdx(21), LkGmblr-Def/EndRdx/Rchg(45)
Level 22: Stamina -- P'Shift-End%(A), P'Shift-EndMod(34), P'Shift-EndMod/Acc(34), P'Shift-EndMod/Rchg(34)
Level 24: Combat Jumping -- LkGmblr-Rchg+(A), LkGmblr-Def(25), LkGmblr-Def/EndRdx(25)
Level 26: Boxing -- RzDz-Acc/EndRdx(A)
Level 28: Tough -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/EndRdx/Rchg(31), RctvArm-EndRdx(39), RctvArm-ResDam(45)
Level 30: Death Shroud -- C'ngBlow-Acc/Dmg(A), Erad-Acc/Dmg/EndRdx/Rchg(37), Erad-Dmg(37), C'ngBlow-Acc/Rchg(43), Erad-%Dam(43), C'ngBlow-Dmg/EndRdx(43)
Level 32: Weave -- LkGmblr-Rchg+(A), LkGmblr-Def(33), LkGmblr-Def/EndRdx(33)
Level 35: Energy Transfer -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(36), KntkC'bat-Dmg/Rchg(36), KntkC'bat-Dmg/EndRdx/Rchg(36)
Level 38: Total Focus -- P'ngS'Fest-Acc/Dmg(A), P'ngS'Fest-Dmg/EndRdx(40), P'ngS'Fest-Dmg/Rchg(40), C'ngImp-Acc/Dmg/EndRdx(40)
Level 41: Chilblain -- Thundr-Acc/Dmg(A), Thundr-Acc/Dmg/EndRdx(42), Thundr-Dmg/Rchg(42), Thundr-Acc/Dmg/Rchg(42), Thundr-Dmg/EndRdx(45), Thundr-Dmg/EndRdx/Rchg(46)
Level 44: Block of Ice -- BasGaze-Acc/EndRdx/Rchg/Hold(A), BasGaze-EndRdx/Rchg/Hold(46)
Level 47: Ice Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(48), Thundr-Dmg/Rchg(48), Thundr-Acc/Dmg/EndRdx(50), Thundr-Dmg/EndRdx/Rchg(50), Thundr-Acc/Dmg/Rchg(50)
Level 49: Soul Transfer -- RechRdx-I(A)
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Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Gauntlet
Level 6: Ninja Run