You definately want 3xHeal in Integration, it's your main defensive power.
What FireKitty said about Integration. 3-slot it with Heals asap.
Also, you don't need to slot endurance reductions in anything except the expensive toggles. Replace the endreds in attacks with damage. You could also get Stamina later, you won't really need it much until you have Focused Accuracy.
I don't know if the slots are in the order you'd take them. If they are, I'd do it a bit differently.
you don't need two accuracies with focused accuracy, switch one for another damage.
Unless you're likely to PvP outside of RV. At which point 2x Acc is essential pretty much.
Changed my build and made sure that every heal power has 3 heal slots now. I went for 3 dam, 1 acc and 1 rech in each attack, but later on I had some spare slots so I added some defdebuffs (it will also help other players). Also every power takes a while to get fully slotted.
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Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder
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Name: OM-garm
Level: 50
Archetype: Scrapper
Primary: Katana
Secondary: Regeneration
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01) --> Sting of the Wasp==> Dmg(1)Acc(3)Dmg(7)Dmg(25)Rechg(37)DefDeBuf(48)
01) --> Fast Healing==> Heal(1)Heal(5)Heal(21)
02) --> Flashing Steel==> Dmg(2)Acc(3)Dmg(9)Dmg(23)Rechg(37)DefDeBuf(48)
04) --> Quick Recovery==> EndMod(4)EndMod(5)EndMod(15)
06) --> Reconstruction==> Rechg(6)Rechg(7)Rechg(13)Heal(23)Heal(36)Heal(36)
08) --> Divine Avalanche==> Acc(8)Dmg(9)Dmg(13)DefBuf(37)Rechg(39)DefBuf(43)
10) --> Dull Pain==> Rechg(10)Rechg(11)Rechg(11)Heal(15)Heal(21)Heal(34)
12) --> Combat Jumping==> DefBuf(12)
14) --> Super Jump==> Jump(14)
16) --> Integration==> Heal(16)Heal(17)Heal(17)
18) --> The Lotus Drops==> Acc(18)Dmg(19)Dmg(19)Dmg(25)Rechg(40)DefDeBuf(48)
20) --> Hurdle==> Jump(20)
22) --> Health==> Heal(22)Heal(45)Heal(46)
24) --> Resilience==> DmgRes(24)
26) --> Soaring Dragon==> Acc(26)Dmg(27)Dmg(27)Dmg(36)Rechg(40)DefDeBuf(46)
28) --> Instant Healing==> Rechg(28)Rechg(29)Rechg(29)Heal(31)Heal(34)Heal(34)
30) --> Build Up==> Rechg(30)Rechg(31)Rechg(31)
32) --> Golden Dragonfly==> Acc(32)Dmg(33)Dmg(33)Dmg(33)Rechg(40)DefDeBuf(46)
35) --> Stamina==> EndMod(35)EndMod(43)EndMod(43)
38) --> Hasten==> Rech(38)Rechg(39)Rechg(39)
41) --> Focused Accuracy==> EndRdx(41)TH_Buf(42)TH_Buf(42)TH_Buf(42)
44) --> Conserve Power==> Rechg(44)Rechg(45)Rechg(45)
47) --> Boxing==> Acc(47)Dmg(50)
49) --> Tough==> DmgRes(49)DmgRes(50)DmgRes(50)
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01) --> Sprint==> Empty(1)
01) --> Brawl==> Empty(1)
01) --> Critical Hit==> Empty(1)
02) --> Rest==> Empty(2)
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Looks pretty good to me! I'm not sure the defdebuff is worth slotting but you can always change them to something else if it isn't. Regarding slotting order, I'd try to get the damaging (ie non Divine Avalanche) attacks 4-slotted pretty early, as well as 5 slots in Reconstruction. Slotting the passives can wait a bit more.
I'd try and get Build Up a lot sooner.
I'm not sure you need Recharges in all your attacks with Hasten. A lot of those Katana attacks recharge pretty quick.
Resilience is only needed if you are going to do a lot of PvP and if so then extra accuracies in your attacks would be better.
I don't think you'll need Conserve Power along with Stamina and Quick Recovery, but then again if they don't resolve the current Endurance problem maybe you will.
I'm running Focused Accuracy on a lvl 47 MA/Regen build and I have to turn it off when fighting anything that saps End (Carnies, Malta, anything with Elec attacks). I have three accuracies in all attacks, but its amazing the difference FA makes when you start seeing "Deflected" popping up when you miss.
With the current End probs, I'm considering swapping out one accuracy for an End Red in each attack and trying to run FA permanently. Attacks drain much more End/sec when scrapping than a few toggles (with the exception of Flight 
).
[color=dodgerblue] err not much point in the defense debuffs tbh
Have to agree with Lui: No point in them at all, the -def barely lasts till the next attack. I'd suggest tweaking DA's slotting though, it won't quite double stack all the time (when hasten is down) without one recred SO.
To give you an idea, my build is below: My 50 kat/regen's been very very good in PVE (for PVP the power order is fine except for maybe taking tactics for +perception, but would need a few more accs for pre-FA levels). About the only change I'd consider now would be to switch TP Foe and TP to Combat Jumping and SJ. At the moment if I get Speed Boosted, positioning myself for cone attacks is a bit of a pain without Combat Jumping.
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Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder - (http://sherksilver.coldfront.net/index.php)
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Name: Maelwys
Level: 50
Archetype: Scrapper
Primary: Katana
Secondary: Regeneration
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01) --> Sting of the Wasp==> Acc(1) Dmg(3) Dmg(5) Dmg(7)
01) --> Fast Healing==> Heal(1) Heal(9) Heal(9)
02) --> Flashing Steel==> Acc(2) Dmg(3) Dmg(5) Dmg(7)
04) --> Reconstruction==> Rechg(4) Rechg(13) Rechg(23) Heal(25) Heal(31)
06) --> Quick Recovery==> EndMod(6) EndMod(11) EndMod(11)
08) --> Divine Avalanche==> Acc(8) Acc(15) Rechg(15) DefBuf(21) DefBuf(21) DefBuf(40)
10) --> Build Up==> Rechg(10) Rechg(13) Rechg(40)
12) --> Teleport Foe==> Acc(12)
14) --> Teleport==> Range(14)
16) --> Integration==> Heal(16) Heal(17) Heal(17) EndRdx(19)
18) --> Dull Pain==> Rechg(18) Rechg(19) Rechg(23) Heal(25) Heal(31)
20) --> Hurdle==> Jump(20)
22) --> Health==> Heal(22) Heal(36) Heal(36)
24) --> Stamina==> EndMod(24) EndMod(29) EndMod(31)
26) --> Soaring Dragon==> Acc(26) Dmg(27) Dmg(27) Dmg(29) Rechg(34) EndRdx(40)
28) --> Instant Healing==> Rechg(28) Rechg(37) Rechg(37) Heal(43) Heal(43)
30) --> Resilience==> DmgRes(30)
32) --> Golden Dragonfly==> Acc(32) Dmg(33) Dmg(33) Dmg(33) Rechg(34) EndRdx(34)
35) --> Hasten==> Rechg(35) Rechg(36) Rechg(37)
38) --> Air Superiority==> Acc(38) Dmg(39) Dmg(39) Dmg(39) Rechg(46)
41) --> Focused Accuracy==> EndRdx(41) EndRdx(42) EndRdx(42) TH_Buf(42) TH_Buf(43)
44) --> Laser Beam Eyes==> Acc(44) Dmg(45) Dmg(45) Dmg(45) Rechg(46) Rechg(46)
47) --> Energy Torrent==> Acc(47) Rechg(48) Rechg(48) EndRdx(48) Dmg(50) Dmg(50)
49) --> Revive==> Rechg(49) Rechg(50)
---------------------------------------------
01) --> Power Slide==> Run(1)
01) --> Sprint==> Jump(1)
01) --> Brawl==> Acc(1)
01) --> Critical Hit==> Empty(1)
02) --> Rest==> Rechg(2)
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I had Tough at about 30-35 but respecced it out as unnecessary and a waste of two slots. I also respeced out of The Lotus Drops since I didn't like it... same low damage as FS but with much higher recharge/end cost.
With Golden Dragonfly and Soaring Dragon I can pretty much keep any one enemy (up to EB level at least) off it's feet, but Air Supp makes SURE of it... Actually, Air Supp alone can keep an enemy off its feet...
Energy Torrent I've found to be very useful, it's a very high % chance for cone knockdown (does knockback only on -1s or lower) and gives my toon decent AOE damage with Flashing Steel and Soaring Dragon... and it's also a fun way of negating alphas or stopping multiple mobs from attacking another player.
Air Supp and Laser Eyes have the recred SOs in them so they form a no-gap, cyclical attack chain when hasten is running (even without hasten they're pretty close to no-gaps, especially with the odd ET thrown in!). After 40+ levels it's nice to have a backup chain that doesn't do lethal damage but Energy/Smashing! 
Can attain superb defense (45%, which without tohit buffs will floor any PvE enemy's tohit in i7) with decent damage output by chaining DA-GD-DA-SD over and over. Combined with the Knockdown in Air Supp. and ET it's a great way of taking down big +5 bosses. In i6 I successfully soloed Paladin as an AV and Infernal as a +4 EB with that tactic, and at high levels I can usually keep two +4 bosses constantly off their feet with the sheer amount of knockup/knockdown in this build.
Haven't had much experience with it in i7 yet, but was able to solo a NRG/INV Brute, two Heavies (not both at once, but they seem very weak to knockdown) and a few Pillboxes fairly easily in RV the other night during the AV-badge event on defiant... That was just with IH/Dull Pain and my standard high-damage attacks, not bothering to even use DA let alone keep it double-stacked.
... the two slots in Revive? I used to have one Endmod SO in it, but I had one slot left over at 50 and it was either that or another Heal SO in Instant Healing (you don't need the 3rd Heal slot in Dull Pain to cap your HP if you get the two HP+ accolades) and I was getting sick of waiting between rezzes in GM/Monster attacks...
Adding a third Heal SO into Reconstruction, IH or Dull Pain gives only a very slight healing increase over 2 SOs (Eg. 49% instead of 44% in the case of Reconstruction). I'd say it's only worth it if you have a surplus of slots.
I still have resilience in at 30 from i6 as a counter to toggle dropping NRGs in PvP. Since the big Toggle Dropping nerf it's less useful, but still prevents sufficient disorients being stacked on me to break through integration.
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Strengths?
+ Heavy Survivability in Regen/Healing and on-demand defense
+ An obscene amount of soft control with all that Knockup/down.
+ Mixture of damage types, backup energy/smashing chain.
+ Switchable between very High DPS, or Good DPS and very high defense.
+ +Perception and good accuracy with FA
+ No downtime. Have never ran low on END against anything except certain EBs and sappers.
+ Carnie missions are easy. Doesn't care about psi damage and has high END regen.
+ Best travel power in the game (IMHO, and with a good bind!)
+ Self rez is useful!!
Weaknesses in this build? Three that I can think of:
+ Heavy Spike Damage (Tough would help very slightly here vs S/L damage, stacked DA usually helps)
+ Heavy Prolonged Endurance Drain (Though QR, Geas of the Kind ones or stacked DA helps a lot)
+ Certain PvP status effects (Repel and fear. MoG gives repel protection but I consider it essentially useless)
Certain TP self tactics can help against repel, but only breakfrees can stop me from getting chain feared.
One last point:
If you have your heart set on "Tough", Don't put any slots in Boxing or Kick. They are basically useless as attacks since they are very low damage with low magnitude effects, and also cause you to put away your weapon which you'll need to redraw before using any katana moves.
Air Supp. is different in that it's 100% Knockdown chance and as such is a useful "Get AWAY from me!" tool immediately after using clickyheals or Hasten (which will also cause weapon redraw). Apart from Build Up and your other Katana moves, only Brawl does not cause the weapon redraw... and it's not worth slotting!
Thank you all for your help
I will tweak my build later on (didn't even notice I slotted boxing 
), but have no time to do it today. For this build I have exactly enough slots (well I think I do, only lvl 12 atm), but will see if I can move some around perhaps 2 acc 2 dam before FA?). The high end attacks are yet to be tested (missed the test server event), but DA is double stacked most of the time now (no SOs yet) so with SOs will I be able to stack 3?
As I said, going to tweak the build later
You can get DA to double-stack constantly with a VERY VERY SLIGHT 3rd overlap with one recharge SO. It's basically impossible to get a 3rd up constantly... and even if you manage to get that much +recharge, it'd mean you were just using DA as your entire attack chain.
At high levels, usually you'll be alternating between Soaring Dragon and Golden Dragonfly, with either Sting of the Wasp or an AOE/Cone attack thrown in as 'fillers' depending on what you're fighting. You can use DA in a normal attack chain, but if you slot it for defense it eats into your DPS a lot so I generally save it for when I need to effectively solo very large mobs or higher-level Bosses/EB.
There's occasionally a situation in teams where it's useful too... like when the rest of your team faceplants and your're up against about 3 mobs worth of invincible-level enemies... Dull Pain, IH, Hasten and Start stacking DA-SD-DA-GD... you might even win...
My main is a Stone/DA Brute and when I got CoH I went for the exact opposite: regeneration. I don't have any experience with scrappers, but this is the build I came up with. Any tip/suggestion will help
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Exported from Ver: 1.7.6.0 of the CoH_CoV Character Builder
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Name:
Level: 50
Archetype: Scrapper
Primary: Katana
Secondary: Regeneration
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01) --> Sting of the Wasp==> Acc(1)Dmg(3)Acc(15)Dmg(17)Rechg(23)EndRdx(25)
01) --> Fast Healing==> Heal(1)Heal(9)Heal(13)
02) --> Flashing Steel==> Acc(2)Dmg(3)Acc(13)Rechg(17)EndRdx(23)DefDeBuf(25)
04) --> Quick Recovery==> EndMod(4)EndMod(5)EndMod(5)
06) --> Reconstruction==> Heal(6)Rechg(7)Rechg(7)Rechg(37)Heal(45)Heal(46)
08) --> Divine Avalanche==> Acc(8)DefBuf(9)Acc(15)DefBuf(21)DefBuf(21)Dmg(34)
10) --> Dull Pain==> Rechg(10)Rechg(11)Rechg(11)Heal(34)Heal(39)Heal(43)
12) --> Combat Jumping==> DefBuf(12)
14) --> Super Jump==> Jump(14)
16) --> Integration==> EndRdx(16)
18) --> The Lotus Drops==> Acc(18)Acc(19)Dmg(19)Dmg(40)Rechg(40)EndRdx(40)
20) --> Hurdle==> Jump(20)
22) --> Health==> Heal(22)Heal(37)Heal(46)
24) --> Stamina==> EndMod(24)EndMod(43)EndMod(46)
26) --> Soaring Dragon==> Acc(26)Acc(27)Dmg(27)Dmg(31)Rechg(34)Dmg(36)
28) --> Instant Healing==> Rechg(28)Rechg(29)Rechg(29)Heal(37)Heal(43)Heal(48)
30) --> Build Up==> Rechg(30)Rechg(31)Rechg(31)
32) --> Golden Dragonfly==> Acc(32)Acc(33)Dmg(33)Dmg(33)Rechg(36)Dmg(36)
35) --> Resilience==> DmgRes(35)
38) --> Hasten==> Rechg(38)Rechg(39)Rechg(39)
41) --> Focused Accuracy==> EndRdx(41)TH_Buf(42)TH_Buf(42)TH_Buf(42)EndRdx(48)
44) --> Conserve Power==> Rechg(44)Rechg(45)Rechg(45)
47) --> Boxing==> Acc(47)Acc(48)
49) --> Tough==> EndRdx(49)DmgRes(50)DmgRes(50)DmgRes(50)
---------------------------------------------
01) --> Sprint==> Empty(1)
01) --> Brawl==> Empty(1)
01) --> Critical Hit==> Empty(1)
02) --> Rest==> Empty(2)
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