Posting your build would help a lot but from what I know about Claws its major strength is knockback and the perma damage buff from follow up (I've heard claws does the most dps over a longer period).
A well slotted aid self is pretty important for SR in the zones also slotting travel powers and fitness (swift/hurdle for unsuppressed movement) important for zones 
thePhilosopher Martial Arts/Regen/Fire Scrapper
theRegulator Empathy/Energy/Soul Defender
Total Inertia Ice Blast/Kinetics/Psy Corruptor
Total Inferno Ice Blast/Thermal/Leviathan Corruptor
As Phil mentioned, Aid Self is very useful. Beyond that, just look at some of the standard PvP mantra's such as 2 ACC in everything, SS coupled with Combat jump(3 jump enhances) and hurdle(3 jump enhances) for maximum unsurpressed mobility.
With fitness(for stamina), Speed(for SS, hasten not really needed on an SR but you need SS so no point skipping it) and leaping for Combat Jump(could skip this pool entirely or add SJ for more mobility), you're also left with an additional pool if you need it.
Presence pool would give you some fear attacks which there's not much resistance to, Fighting will give you tough to make you a little more hardy, TP foe can be useful and leadership will give you a bit more protection against stalkers.
A quick glane in the scrapper forum will show you some PvP Claw/* and */SR discussions for PvP so you can merge some of those for a more rounded build.
Best bet will be to post your build though so people can see where you may be going wrong.
hey there, im also a claws / SR made mine b4 I7 and i only ever PVE'd really, but once i hit 50 i started to realize theres not much left for me but pvp, so i looked into some stuff to help the claws/ SR in pvp.
as already mentioned above, aid self is very handy in PvP and is well worth taking, also followup slotted 3 recharge is very nice too, i also took hasten, this helps keep me double followup'd through my attack chain, which once your through your first round can start hurting ppl
with claws and pvp you then have to decide if you want to take some of the AE's.This is up to you, and may also depend if your planning any PVE.personally i went for more single target attack chain, but still took eviscirate because the damage in that is good enough for me to use on any single foe.
all in all though, my advice would be copy to the test server, and play with some builds, it took me a while to come up with one i liked, and there is a few diff ones to choose from.
hope this helped
The main thing it has going for it is Focus - one of your most powerful attacks, its *ranged*, fast to animate and fast to recharge.
There are other things about SR and Claws which are good for PvP but Focus is what it revolves around. Effectively you're a blaster with extremely good defences, like that other tank mage, spines/regen.
I wasn't going to get Focus for concept reasons, instead was going to pick Confront - You can see stalkers, taunt them and they can't do diddly squat to squishies
[ QUOTE ]
I wasn't going to get Focus for concept reasons, instead was going to pick Confront - You can see stalkers, taunt them and they can't do diddly squat to squishies
[/ QUOTE ]
It's still one of the top Claws powers ranged or not. You might want to test using Confront before going for it - Taunt in PvP has changed and it's not as effective as it was. SR alone also won't let you see a Stalker running both Hide and Stealth - not that every Stalker does this though.
[ QUOTE ]
[ QUOTE ]
I wasn't going to get Focus for concept reasons, instead was going to pick Confront - You can see stalkers, taunt them and they can't do diddly squat to squishies
[/ QUOTE ]
It's still one of the top Claws powers ranged or not. You might want to test using Confront before going for it - Taunt in PvP has changed and it's not as effective as it was. SR alone also won't let you see a Stalker running both Hide and Stealth - not that every Stalker does this though.
[/ QUOTE ]
Indeed, but I try and make my builds balanced to suit my playstyle which is a mix between PvE / PvP - Confront on a SR scrapper could come in damn handy, used effectively. Also, FA would see through Hide + Stealth (as an SR, I'd also pick up Conserve Power.. but meh).
Stealth / Hide Stalkers, as an SR, wouldn't really bother me - with Quickness and my non-travel power movement (intended for extreme melee combat freedom) I can outrun them anyway (Stealth makes you somewhat slower).
Throw a couple of yellows into that and you're singing.
However, I do know that Taunt got nerfed somewhat for PvP, but it should work in the same vein as Placate - they can't target anyone else, they're only invisible to you - so with a good team you could probably have the team either buff / heal / rez you and take care of the otherwise distracted Stalker.
Thank you all for your feedback !
I actually don't have SS but I rather took SJ. Now reading your comments I'm probably going to change this and combine SS with hurdle.
I did take SelfAid but the problem is that I didn't get to fit it in until lvl32 which means that I can't use it in Siren's Call which is a problem...
My attack powers are mostly slotted with 3 damage and 2 accuracy and I did take focus as it is indeed the best attack (as it is ranged with knockback) that I have in PVP.
I also have follow up but I didn't take slash (not sure if it's worth eventhough it has the -DEF)
Something else I was wondering about is if it makes sense to slot brawl. I heard/read brawl can be used to interrupt a Stalkers Assasin attack and that it has a chance to detoggle your enemies powers but would it need accuracy slotting for it ?
One more thing is there anything against being 'terrorized' ? It seems I'm quite helpless against it and have been beaten because I was constantly 'terrorized'
I would stick with CJ & SJ unless you are convinced you don't need vertical movement.
You should be able to fit Aid Self into your build pre-level 30, I have with a MA/SR.
Any successful attack will interrupt a stalker's AS the problem is you won't be able to see a stalker with both Hide and Stealth, you can see one with Hide only if you have SR as a secondary and if you can see them, you can hit them, unless you get placated...
If you get placated just start moving - you may be able to see a stalker who has placated you but you can't target them and so can't attack them; keep moving, wait until you can target, then attack. If you get placated a stalker can still get a critical if they hit you with one of their standard attacks, the majority of stalker players have a poor understanding of their powers and won't even bother.
Brawl used to have a high chance of detoggling (it's now 5%), all detoggling for all powers has been reduced, it's not worth slotting brawl.
Carry BFs to defend against Fear, or team with someone who can buff you (like an empathy defender with Clear Mind). Fear isn't always that powerful - once you are feared, if you are attacked you should be able to move away or take another action like attack although your accuracy will be debuffed at least -20%.
I have a level 50 CL/SR and in the last few days I've been playing some PVP with it and I must conclude that's it's not really working for me. I heard to that CL/SR should be good for PVP so I guess I'm doing something wrong.
I'm pretty sure there are several reasons it's not working properly and one being me not used to playing PVP.
On the other hand I'm also wondering if I build my toon right (I tried to respec if for PVP) and so I hope some people can give me some tips. I'm not posting my current toon specs because that would focus your attention to hard on the way I built the toon and how you would change it.
I just would like to hear from people what powers I should surely have and which not.. How to slot them etc... If you like to show me a whole build that would be great as well !
Additionally any Hints/tips on how to play this specific build would be welcome as well.
Thanks in advance for all your help !