Staff/Dark/Fire could use some critique

So I'm homing in on level 35 on my Staff/Dark stalker and I'm really loving this combo -- I've been looking at builds for such a pairing, so I decided to make up my own, and this is what I've come up with so far... Even though it LOOKS good, to me, I feel there are some weaknesses and mistakes in the build that I'm overlooking. I was hoping y'all could address that.

I just finished putting 10 bil into my 50+2 crab and +3 SS/WP brute, so budget and availability of IOs aren't too drastic of a concern; I have a few of these IOs lying around and a large pool of influence, so hit me with your best shot! I'm looking to make a stalker with solid defense, excellent offense and great self-sufficiency. Without further adue... FOOTNOTES!


Good things the build boasts:
*Solid recharge rating. The longest-recharging attack in my attack chain is under 5s recharge
*I feel its overall survivability is very good, with resistance and defense are at excellent numbers. S/L/NRG/NEG and AoE softcap (with melee softcap when Guarded Spin lands), 58.5% S/L 41.5% Fire/Cold, 26.5% NRG, 53.5% NEG, 26.5% TOX and 45.5% PSI.
*Permahasten
*Good debuffs and utility through Guarded Spin, Fury of the Gladiator and Force Feedback procs, Theft of Essence in Dark Regeneration and other goodies.

Bad things the build totes:
*Endurance recovery versus usage is iffy.
*Mediocre protection from Fire and Cold.
*I only have one KB protection IO, meaning I may have to ditch permahasten for another for reliable -KB magnitude. Not a huge deal as Permahasten isn't super important on Stalkers, right?

Questions and concerns about the build:
*Endurance management. Will I have an endurance reduction bonus for my attacks, coupled with a recovery rate high enough to permit the use of Agility Core Paragon over its Cardiac counterpart? The recharge and defense look sweet as heck, but... what's the alpha for me?
*Ancillary/Epic: Is Fire a decent choice? I'd kind of prefer to go for a more damaging epic like Fire over anything else, but if you can make a case for any other epic then I'd love to hear your thoughts!
*Mercurial Blow over Precise Strike for the -DEF... Crazy or cool?
*Should I place my Fury of the Gladiator 2-piece in Eye of the Storm or switch it over to Guarded Spin?
*Scirocco's Dervish 2-piece; was this a dumb choice?

All in all, here's the building block and the build itself for critique. Thanks in advance!:


Villain Plan by Mids' Villain Designer 1.956
http://www.cohplanner.com/

Click this DataLink to open the build!

Dreadwrought: Level 50 Natural Stalker
Primary Power Set: Staff Fighting
Secondary Power Set: Dark Armor
Power Pool: Leaping
Power Pool: Speed
Power Pool: Fighting
Ancillary Pool: Blaze Mastery

Villain Profile:
Level 1: Mercurial Blow -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(3), KntkC'bat-Dmg/Rchg(5), KntkC'bat-Dmg/EndRdx/Rchg(9), Mako-Acc/Dmg/EndRdx/Rchg(13)
Level 1: Hide -- LkGmblr-Rchg+(A), LkGmblr-Def(43), SW-ResDam/Re TP(46)
Level 2: Guarded Spin -- Erad-Dmg(A), Erad-Dmg/Rchg(3), Erad-Acc/Dmg/Rchg(9), Sciroc-Acc/Dmg(13), Sciroc-Dmg/EndRdx(15), LkGmblr-Rchg+(37)
Level 4: Dark Embrace -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(5), RctvArm-ResDam/EndRdx/Rchg(15), RctvArm-ResDam(40)
Level 6: Assassin's Staff -- SStalkersG-Acc/Dmg(A), SStalkersG-Dmg/Rchg(7), SStalkersG-Acc/Dmg/Rchg(7), SStalkersG-Dmg/EndRdx/Rchg(11), SStalkersG-Acc/Dmg/EndRdx/Rchg(11), SStalkersG-Rchg/Hide%(17)
Level 8: Build Up -- Rec'dRet-ToHit(A), Rec'dRet-ToHit/Rchg(48)
Level 10: Shadow Dweller -- LkGmblr-Rchg+(A), LkGmblr-Def(48), Krma-ResKB(50)
Level 12: Combat Jumping -- LkGmblr-Rchg+(A), LkGmblr-Def(46)
Level 14: Hasten -- RechRdx-I(A), RechRdx-I(50)
Level 16: Obsidian Shield -- S'fstPrt-ResDam/Def+(A), GA-3defTpProc(17)
Level 18: Eye of the Storm -- Erad-Dmg(A), Erad-Acc/Dmg/Rchg(19), Erad-Dmg/Rchg(19), FotG-ResDeb%(25), FotG-Dam/Rech(29), FrcFbk-Rechg%(46)
Level 20: Dark Regeneration -- Theft-+End%(A), Theft-Heal(21), Theft-Heal/Rchg(21), Theft-Acc/Heal(29), Theft-Acc/EndRdx/Heal(31), Theft-Acc/EndRdx/Rchg(50)
Level 22: Placate -- Range-I(A)
Level 24: Murky Cloud -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(25), RctvArm-ResDam/EndRdx/Rchg(37), RctvArm-ResDam(40)
Level 26: Serpent's Reach -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(27), Thundr-Dmg/Rchg(27), Thundr-Acc/Dmg/Rchg(31), Thundr-Acc/Dmg/EndRdx(34), Thundr-Dmg/EndRdx/Rchg(40)
Level 28: Kick -- Empty(A)
Level 30: Tough -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(31), RctvArm-ResDam/EndRdx/Rchg(34), RctvArm-ResDam(37)
Level 32: Sky Splitter -- KntkC'bat-Acc/Dmg(A), KntkC'bat-Dmg/EndRdx(33), KntkC'bat-Dmg/Rchg(33), KntkC'bat-Dmg/EndRdx/Rchg(33), Mako-Acc/Dmg/EndRdx/Rchg(34)
Level 35: Char -- BasGaze-Acc/Hold(A), BasGaze-Acc/EndRdx/Rchg/Hold(36), BasGaze-EndRdx/Rchg/Hold(36), BasGaze-Slow%(39)
Level 38: Weave -- LkGmblr-Rchg+(A), LkGmblr-Def(39), LkGmblr-Def/EndRdx(39)
Level 41: Fire Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(42), Thundr-Dmg/Rchg(42), Thundr-Acc/Dmg/Rchg(42), Thundr-Acc/Dmg/EndRdx(43), Thundr-Dmg/EndRdx/Rchg(43)
Level 44: Fire Ball -- Posi-Acc/Dmg(A), Posi-Dmg/EndRdx(45), Posi-Dmg/Rchg(45), Posi-Acc/Dmg/EndRdx(45), Posi-Dam%(48)
Level 47: Melt Armor -- Achilles-ResDeb%(A)
Level 49: Soul Transfer -- Amaze-ToHitDeb%(A)
Level 1: Assassination
Level 1: Brawl -- Empty(A)
Level 1: Prestige Power Dash -- Empty(A)
Level 1: Prestige Power Slide -- Empty(A)
Level 1: Prestige Power Quick -- Empty(A)
Level 1: Prestige Power Rush -- Empty(A)
Level 1: Prestige Power Surge -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 4: Ninja Run
Level 4: Swift -- Empty(A)
Level 4: Health -- Mrcl-Rcvry+(A)
Level 4: Hurdle -- Empty(A)
Level 4: Stamina -- P'Shift-EndMod(A), P'Shift-EndMod/Rchg(23), P'Shift-EndMod/Acc(23), P'Shift-End%(36)
Level 1: Combo Level 1
Level 1: Combo Level 2
Level 1: Combo Level 3
Level 50: Agility Core Paragon
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I had only a single -4 kb in my tw/da scrapper, and I had no problems with knockback. Permahasten imo is a lot better than having an extra -4 kb. A lot might disagree, but you are a stalker, and not intending to be hit. Given your defense, and the fact you would hardly be getting hit in the first place, is it really worth it blowing your hasten-driven astrikes for just a few points kb protect?

Well you could always replace combat jumping with hover. that would help with the knockback since hover has knock back protection in it automaticaly.

I see you probably have tons of energy issues...since you have 6 active toggles going....
And a hasten that eats a big chunk of energy every so often. i think i missed a few toggles also.
You might try only slotting stamina for 3 slots total with the endurence recovery performance shifter and the chance for +5 energy performance shifter.
And slot a regular Stamina recovery invention into stamina....that will net you alot better energy recovery.
Then slot health with the numina enhance recovery/regenration one.
Which will increase your recovery of energy even more.

if knockback is still a huge issue after selecting hover....then you should take one slot out of weave and either make that another karma in I would suggest low level defense power so you always will have it even while exemplared. (hide would work well for that)
I suggest that becasue you wouldnt notice the missing the 1% defense one of those slots in weave gives you.