That's a pretty expensive build. What are you working towards?
You stacked 43% recharge but only 1 slot in Hasten?
I'd advise for more +max endurance over +recovery where available. Also might consider slotting FS with Accurate -to-hit debuff instead of fear if you're using it as your opener/alpha breaker.
Might consider adding more slots to Shadowfall to increase defense/resistance or both.
You took Tenebrous Tentacles but no Nightfall? They make a good 1-2 punch.
Thanks for the feedback, wasn't that sure what to aim for with the build to be honest, bit of everything in there... Wanted to see what I had done ok with and of course what I have done wrong!
Done some reading on the D3 and its main strength it seems to me is the -acc buff, so would I need to add to that or is it good to go straight off and look at improving as you have mentioned end recov or end max?
The -to-hit debuff is what makes a D3 great. However you will not need to slot your secondary attacks with them. You'll get enough from your primary and any base debuffs from your secondary blasts. Slot the blasts like blasts.
Like a stated before, you want to slot for max end over recovery. You'll still end up with +recovery from bonuses on sets and any uniques. the problem is there are no +max end uniques. Stacking +max end with accolades give you more recovery than stacking recovery. I know that sounds weird but recovery is based off your max end, not base end.
Again thanks for the heads up and info, will relook at the build after work today. And see what I can come up with, will post new build later for more advise. Thanks again Jebe 
Updated build, gone for Endrec & Max End!
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
Genii Cucullati: Level 50 Magic Defender
Primary Power Set: Dark Miasma
Secondary Power Set: Dark Blast
Power Pool: Flight
Power Pool: Fitness
Power Pool: Leadership
Power Pool: Speed
Ancillary Pool: Dark Mastery
Hero Profile:
Level 1: Twilight Grasp -- Theft-Acc/Heal(A), Theft-Acc/EndRdx/Heal(3), Theft-Acc/EndRdx/Rchg(5), Mrcl-Heal/Rchg(13), Mrcl-Heal/EndRdx/Rchg(19), Acc-I(23)
Level 1: Dark Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/Rchg(7), Thundr-Acc/Dmg/Rchg(39), Thundr-Acc/Dmg/EndRdx(40), Acc-I(48)
Level 2: Tar Patch -- RechRdx-I(A), RechRdx-I(3), RechRdx-I(5), Slow-I(13)
Level 4: Darkest Night -- DampS-ToHitDeb(A), DampS-ToHitDeb/EndRdx(11), DampS-ToHitDeb/Rchg/EndRdx(11)
Level 6: Gloom -- Thundr-Acc/Dmg(A), Thundr-Dmg/Rchg(7), Thundr-Acc/Dmg/Rchg(40), Thundr-Acc/Dmg/EndRdx(42), Acc-I(46)
Level 8: Shadow Fall -- Aegis-Psi/Status(A), S'fstPrt-ResKB(9), S'fstPrt-ResDam/Def+(9), S'fstPrt-ResDam/EndRdx(15)
Level 10: Hover -- Zephyr-Travel(A), Zephyr-Travel/EndRdx(15)
Level 12: Swift -- Run-I(A)
Level 14: Fly -- Flight-I(A)
Level 16: Tenebrous Tentacles -- Ragnrk-Acc/Dmg/Rchg(A), Ragnrk-Acc/Rchg(17), GravAnch-Acc/Immob/Rchg(17), GravAnch-Immob(19), Ragnrk-Dmg(25), Ragnrk-Dmg/EndRdx(27)
Level 18: Health -- Numna-Regen/Rcvry+(A), Mrcl-Rcvry+(36), RgnTis-Regen+(50)
Level 20: Stamina -- EndMod-I(A), EndMod-I(21), EndMod-I(21)
Level 22: Fearsome Stare -- Abys-Acc/Rchg(A), Abys-EndRdx/Fear(23), Abys-Acc/EndRdx(27), Abys-Fear/Rng(29), Abys-Acc/Fear/Rchg(36), RechRdx-I(46)
Level 24: Howling Twilight -- Amaze-Acc/Rchg(A), Amaze-Stun(25), Stpfy-Acc/Rchg(29), Stpfy-Acc/Stun/Rchg(31), Stpfy-Acc/EndRdx(36)
Level 26: Maneuvers -- GftotA-Def(A), GftotA-Def/EndRdx(31), GftotA-Def/Rchg(37), GftotA-Def/EndRdx/Rchg(39)
Level 28: Moonbeam -- Apoc-Dmg(A), Apoc-Dmg/Rchg(31), Apoc-Acc/Dmg/Rchg(40), Apoc-Acc/Rchg(42), Apoc-Dmg/EndRdx(48)
Level 30: Petrifying Gaze -- UbrkCons-Acc/Hold/Rchg(A), UbrkCons-Acc/Rchg(34), BasGaze-Acc/Hold(37), BasGaze-Rchg/Hold(37), BasGaze-EndRdx/Rchg/Hold(39), UbrkCons-Dam%(48)
Level 32: Dark Servant -- EoCur-Acc/Hold/Rchg(A), Enf'dOp-Acc/Immob/Rchg(33), Dct'dW-Heal/EndRdx/Rchg(33), ToHitDeb-I(33), ToHitDeb-I(34), ToHitDeb-I(34)
Level 35: Dark Pit -- Amaze-Acc/Stun/Rchg(A), Amaze-Stun/Rchg(43)
Level 38: Assault -- EndRdx-I(A), EndRdx-I(42)
Level 41: Dark Consumption -- Armgdn-Acc/Dmg/Rchg(A), Armgdn-Acc/Rchg(43), Armgdn-Dmg/Rchg(43), Armgdn-Dam%(46)
Level 44: Dark Embrace -- ImpArm-ResDam(A), ImpArm-ResDam/EndRdx(45), ImpArm-ResDam/Rchg(45), ImpArm-ResDam/EndRdx/Rchg(45)
Level 47: Tactics -- GSFC-Build%(A), EndRdx-I(50), EndRdx-I(50)
Level 49: Hasten -- RechRdx-I(A)
------------
Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Vigilance
------------
[u]Set Bonus Totals:[u]<ul type="square">[*]6% DamageBuff(Smashing)[*]6% DamageBuff(Lethal)[*]6% DamageBuff(Fire)[*]6% DamageBuff(Cold)[*]6% DamageBuff(Energy)[*]6% DamageBuff(Negative)[*]6% DamageBuff(Toxic)[*]6% DamageBuff(Psionic)[*]3% Defense(Smashing)[*]3% Defense(Lethal)[*]3% Defense(Fire)[*]3% Defense(Cold)[*]12.1% Defense(Energy)[*]12.1% Defense(Negative)[*]4.88% Defense(Psionic)[*]3% Defense(Melee)[*]9.88% Defense(Ranged)[*]3% Defense(AoE)[*]7.65% Max End[*]2.75% Enhancement(Terrorized)[*]16.3% Enhancement(RechargeTime)[*]53% Enhancement(Accuracy)[*]83.9 HP (8.25%) HitPoints[*]Knockback (Mag -4)[*]Knockup (Mag -4)[*]37% (0.62 End/sec) Recovery[*]26% (1.1 HP/sec) Regeneration[*]10.1% Resistance(Fire)[*]7.56% Resistance(Cold)[*]3% Resistance(Psionic)[/list]
Let me know what you think...
+7.65% max end is a good start. Hopefully you'll get the +max end accolades. I have something like 23% and I'm still missing Portal Jockey but I have to make sure once I get home since I can't really view the build in comfortable detail at work. In particular, I want to see the end reductions and recharge reductions. Sorry it took me so long to reply, I don't normally view the forums on the weekend.
I'll advise you with some advice! Should you not wish to lose out on any loose change, please change your engine oil every 3000 miles.
...Hey, wait a minute, you're in the UK, you spell defense as defence too, don't you! 
Need some advise regarding a D3 build I have put togther, never played a Defender before, so any and all advise greatfully recieved.
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
Genii Cucullati: Level 50 Magic Defender
Primary Power Set: Dark Miasma
Secondary Power Set: Dark Blast
Power Pool: Flight
Power Pool: Fitness
Power Pool: Teleportation
Power Pool: Speed
Ancillary Pool: Dark Mastery
Hero Profile:
Level 1: Twilight Grasp -- Theft-Acc/Heal(A), Theft-Acc/EndRdx/Heal(3), Theft-Heal/Rchg(3), Mrcl-Heal/Rchg(7), Acc-I(11), RechRdx-I(13)
Level 1: Dark Blast -- Acc-I(A)
Level 2: Tar Patch -- RechRdx-I(A), RechRdx-I(5), RechRdx-I(5), Slow-I(11)
Level 4: Darkest Night -- DampS-ToHitDeb(A), DampS-ToHitDeb/EndRdx(7), DampS-ToHitDeb/Rchg(9)
Level 6: Hover -- Zephyr-Travel(A), Zephyr-Travel/EndRdx(13), Zephyr-ResKB(42)
Level 8: Shadow Fall -- Aegis-Psi/Status(A), S'fstPrt-ResKB(9)
Level 10: Swift -- Run-I(A)
Level 12: Gloom -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(15), Thundr-Dmg/Rchg(15), Thundr-Acc/Dmg/Rchg(19), Thundr-Acc/Dmg/EndRdx(37), Thundr-Dmg/EndRdx/Rchg(39)
Level 14: Fly -- Flight-I(A)
Level 16: Tenebrous Tentacles -- GravAnch-Immob(A), GravAnch-Immob/Rchg(17), GravAnch-Acc/Immob/Rchg(17), GravAnch-Acc/Rchg(19), GravAnch-Immob/EndRdx(27), GravAnch-Hold%(27)
Level 18: Health -- Numna-Regen/Rcvry+(A), Mrcl-Rcvry+(39), RgnTis-Regen+(39)
Level 20: Stamina -- EndMod-I(A), EndMod-I(21), EndMod-I(21)
Level 22: Howling Twilight -- Amaze-Stun/Rchg(A), Amaze-Stun(23), Amaze-Acc/Stun/Rchg(23), Amaze-Acc/Rchg(31), Amaze-EndRdx/Stun(37)
Level 24: Fearsome Stare -- Abys-Acc/Rchg(A), Abys-EndRdx/Fear(25), Abys-Acc/EndRdx(25), Abys-Fear/Rng(31), Abys-Acc/Fear/Rchg(36), RechRdx-I(37)
Level 26: Moonbeam -- Apoc-Dmg(A), Apoc-Dmg/Rchg(31), Apoc-Acc/Dmg/Rchg(34), Apoc-Acc/Rchg(40), Apoc-Dmg/EndRdx(40), Apoc-Dam%(40)
Level 28: Petrifying Gaze -- UbrkCons-Acc/Hold/Rchg(A), UbrkCons-Acc/Rchg(29), UbrkCons-Hold/Rchg(29), UbrkCons-Hold(36), Acc-I(36)
Level 30: Recall Friend -- IntRdx-I(A)
Level 32: Dark Servant -- EoCur-Acc/Hold/Rchg(A), Enf'dOp-Acc/Immob/Rchg(33), Dct'dW-Heal/EndRdx/Rchg(33), ToHitDeb-I(33), ToHitDeb-I(34), ToHitDeb-I(34)
Level 35: Dark Pit -- Acc-I(A), Acc-I(42), RechRdx-I(46), RechRdx-I(46), Dsrnt-I(50)
Level 38: Blackstar -- ToHitDeb-I(A), ToHitDeb-I(43), ToHitDeb-I(43)
Level 41: Dark Consumption -- Sciroc-Acc/Dmg(A), Sciroc-Dmg/Rchg(42), Sciroc-Acc/Rchg(43), Sciroc-Acc/Dmg/EndRdx(46)
Level 44: Dark Embrace -- RctvArm-ResDam(A), RctvArm-ResDam/EndRdx(45), RctvArm-ResDam/Rchg(45), RctvArm-ResDam/EndRdx/Rchg(45), S'fstPrt-ResDam/Def+(50)
Level 47: Soul Drain -- Armgdn-Dmg(A), Armgdn-Dmg/Rchg(48), Armgdn-Acc/Dmg/Rchg(48), Armgdn-Acc/Rchg(48), Armgdn-Dmg/EndRdx(50)
Level 49: Hasten -- RechRdx-I(A)
------------
Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Vigilance
------------
[u]Set Bonus Totals:[u]<ul type="square">[*]6% DamageBuff(Smashing)[*]6% DamageBuff(Lethal)[*]6% DamageBuff(Fire)[*]6% DamageBuff(Cold)[*]6% DamageBuff(Energy)[*]6% DamageBuff(Negative)[*]6% DamageBuff(Toxic)[*]6% DamageBuff(Psionic)[*]4.25% Defense(Smashing)[*]4.25% Defense(Lethal)[*]4.56% Defense(Fire)[*]4.56% Defense(Cold)[*]9.56% Defense(Energy)[*]9.56% Defense(Negative)[*]8% Defense(Psionic)[*]3.63% Defense(Melee)[*]10.5% Defense(Ranged)[*]6.13% Defense(AoE)[*]3.6% Max End[*]46.3% Enhancement(RechargeTime)[*]2.75% Enhancement(Terrorized)[*]85% Enhancement(Accuracy)[*]4% FlySpeed[*]49.6 HP (4.88%) HitPoints[*]4% JumpHeight[*]4% JumpSpeed[*]Knockback (Mag -8)[*]Knockup (Mag -8)[*]MezResist(Immobilize) 1.1%[*]18% (0.3 End/sec) Recovery[*]36% (1.53 HP/sec) Regeneration[*]10.1% Resistance(Fire)[*]10.1% Resistance(Cold)[*]3.13% Resistance(Negative)[*]5% Resistance(Toxic)[*]3% Resistance(Psionic)[*]4% RunSpeed[/list]