Hokay Elerion, I understand to some extent what you mean with that.

We've played ~60 games this weekend, losing 19 with a high of 1809, 10 of those losses being in our last session from the sheer amount of warriors there are in 2s. Allow me to try and describe where things go wrong and hopefully some advice is floating round.
Warriors.
Druids.
Warlocks to some extent, drains going through pillars is frustrating as hell when theres a UA on you.

Gonna talk about how things go presuming warrior/healer setups, which appear to dominate 2v2 and are our worst performance. My lock is usually free to cast, with their dps hitting on me, chasing the healer and draining it dotting and fearing/CoEx'ing occasionally. If he is focussed generally the game is a lot easier and it's a win, but getting melee to not obliterte the felpup and lure me out to heal it and switch to me goes sour generally too. I'm by no means "squishy" (as far as cloth gear can be) with 410 resilience and 12k hp buffed, warriors will just destroy me eventually. I can draw out some pummels and maybe get a quick heal off before a macestun will go off or their druid friend charges warrior intercepts me yada yada shutting me down and having to attempt to bait another pummel having wasted a lot of time with no heals. Obviously I can't get many if at all any burns on their healer because i'm moving so slowly and can't afford to not heal myself, and alas i'm out of mana and we fall over. To the same extent are rogues on me, but a supression during their CD spree usually softens stuff and I can survive long enough because fear actually works *gasp*.
My general strat for tanking such a thing would be keeping renew up, shields on CD, baiting a pummel with MC or a fake cast, maybe even getting a fear off and trinketting to disappear round the pillar and hoping focus procs go off at ideal moments.

This is the main thing i'd like to work on, but I have no idea of warrior weaknesses for a lock/priest setup.

One last thing, trinkets. Currently i'm using Scarab of the Infinite Cycle(Scarab of the Infinite Cycle - Items - World of Warcraft) with a plus to heal of 1422 with it. I could farm some honour for the heal on use one or farm some heroic badges for the hp-on-demand one, or I have Bangle of Endless Blessings (Bangle of Endless Blessings - Items - World of Warcraft) handy in my bags I could try using. Any advice?

Warriors and rogues are very anti-lock/priest, but the basic strategy is to force the healer to play the game, thus opening him up for drains. When the warrior is hitting on you, get him dotted up, CoW to reduce incoming damage, and pull him around a pillar out of his healer's LoS. Make sure to dispel anything but Lifebloomx1 if it's a druid healer. If healer pops out, lock goes to town with fears and drains trying to empty him out. If he doesn't, the warrior is open for a burst kill (make sure you help out on damage if the opportunity for the burst arises). Spell Lock, Fel Domination, Spell Lock, Death Coil buys a lot of extra time when the healer tries to come to the late rescue.

If they go for the pet, unload on the warrior health and/or healer mana (whatever is in range, mana always priority) while delaying the pet death as much as possible. Avoid giving the warrior free damage with whirlwind through pet positioning. If pet drops, lock should resummon VW, at which point you should do your best to stay out of intercept range, because he's almost surely switching to you next.

It's a difficult match because it requires a team that is used to playing "slow death" to switch to "coordinated burst", since you are now the beatdown. It also gives the warrior ample rage to decimate you if healer is allowed to land heals on him easily.

Here's a question to which the answer may or may not be obvious:

Various mechanics in the game reduce damage taken from critical strikes. This cap is 25% damage reduction, but I've only ever seen anyone say that this cap is from resilience and talents alone. My question is, once you get 495 resilience (around 25.04% mitigation or something close to that), does Focused Will still reduce damage taken from critical strikes, and is that an additive reduction or multiplicative?

This question doesn't seem very important, because either way I'll still be going 41 into disc for pain suppression, but as they say, "the more you know."

Even *if* there was a 25% cap on damage reduction to crits that would make Focused Will superflous on incoming crits, Focused Will applies to HITS, as well. And if you have 495 resil four out of five attacks will be hits.

That said, I was under the impression that Focused Will stacks with Resilience for crit damage reduction.

Furthermore...a cap at 25% damage reduction on crits would make Pain Supression way worse than advertised, no?

What do you mean "if"? There have been a lot of tests done on resilience, along with blue posts on the wow forums. There's a "soft cap" on critical strike damage reduction at 25% mitigation. This doesn't make Pain Suppression or Focused Will any worse than it would be otherwise, as you yourself pointed out, when pushing 500 resilience a large percentage of the attacks made against you will be noncrit anyway. It's just something that I'd like to know for sure.

I think he didn´t mean to question the 25 % resilience-cap but the question, whether this cap is also true for the other mentioned effects. I personally strongly tend to think that this cap is only valid for resilience, and stacks with other damage-reducing-stats. I can (nearly) guarantee it for Pain Suppression, as I don´t see any other way how a Pyro-Crit can be reduced to less than 2k (I experienced this in arena lately, with 400 resilience and Pain Suppression active). Thus I also think it stacks with Focused Will, though I can´t verify it. Whether it stacks additive or multiplicative I can´t say. I´m not enough into the games mathematic to investigate that.

Yes, Focused will will further reduce damage taken from crits, and it is a multiplicative calculation. For example, on an attack that hits for 1000 and crits for 2000:
-493+ Resilience, with Focused will: 2000 * .75 * .85 = 1275
-493+ Resilience, without Focused will: 2000 * .75 = 1500
-493+ Resilience, with Focused will and Pain Surpression: 2000 * .75 * .85 * .6 = 765

Critical strike damage reduction is capped at -25% via resilience and other effects which exclusively modify damage taken from critical strikes. Critical strikes can be further reduced by blanket damage reduction like Focused Will and Pain Supression. Picture it this way: every player has a semi-hidden critical strike multiplier that all critical strikes are mulitplied by, and this number can never go below .75. That's the only cap there is.

Thanks for the information, both Benjamin and heel. You have put my mind at ease

I've noticed a rather large trend of top tier arena priests (disc) switching from the [Mystical Skyfire Diamond] to the [Insightful Earthstorm Diamond]. Is this due to the cooldown nerf on the MSD? Or is it mainly due to gem color choices when using epic quality resilience gems (no green epic gem)?

In my case, the choice to switch to [Insightful Earthstorm Diamond] was mostly due to the effect granted by the gem. Many of my casts are instant or at/below 1.5 sec cast time, thus the gem is only valueable in situations when constant Mana Burns or Greater Heals are neccessary and/or possible.

Manareg is usefull in every situation, so i chose the Allround-Metagem.

The requirements are no real problem for any gem, at least for me, as i try to get every socket bonus.
(yellow/blue slots get [Steady Talasite] or [Mystic Dawnstone], red slots get [Royal Nightseye].)

Elaborate please? Enlightenment increases int, spirit and stam by 1/2/3/4/5%, how does this affect the proc?

syeren doesn't argue that Enlightenment affects the proc part of the meta gem, but rather that Enlightenment further increases the mana gained through the meta gem because of the 12 int the gem also grants.

What would make a good entry level PVP belt for my Shadow Priest? He's got Netherweave still.

[Unyielding Girdle] is a fine choice, though of course the S3 belt is better. If you're using your honor for other items, this is one of the few slots you can craft a decent resilience item in!

edit: found the answer to my question

There are some points to argue regarding this specc: Blessed Recovery is genereally considered pretty useless, since it´s overwritten by itself, I´d rather take shadow resilience instead. Also, there´s the question whether you shouldn´t take Misery and Shadow reach. Since I play a disc in arena I can´t really speak out of experience but I personally wouldn´t value Martyrdom very high for a shadow. And Misery adds another dispell-layer. For Shadow Reach I´m quite unsure, I simply don´t know If the reach really is useful or not.

Anyways, I´d either go "deep"-disc (to get imp. Manaburn) and drop the points in Holy completely or drop disc completely, depending on my group-setup. If I put points in disc I´d also take Silent Resolve, given the amount of dispellable spells a SP has on the table.

Hi, let's go over this again: Misery does NOT add dispelable magic debuff, but a non dispelable one, like the Weakend Soul, Mind Flay, etc.

I have to say I´m not totally convinced, but I´m quite sure that misery is a magical debuff and thus can be dispelled. Or am I getting something totally mixed up right there?

Seeing is believing.

Misery Debuff
Misery - Spells - World of Warcraft

Shadow Vulnerability Debuff
Shadow Vulnerability - Spells - World of Warcraft

Now, I don't have a screenshot to prove, but I don't think I'm wrong.

Keep in mind that as your resilience increases, non-crit hits will start to proc "on-crit" talents. For some talents it's good (Martyrdom, Focused Will), but for others it's bad - specifically Blessed Recovery. Picture this; you just got PoM-Pyro'ed for 4k. You should be getting back 1k, after one tick however your BR procs again on a white hit of 100. This overwrites the previous one (you lose the potential 666 health? - not sure how many ticks BR has) and now you're going to get a whopping 25 health back...

Misery cannot be dispelled. Instead it rides on the coattails of one of your magic debuffs. When SWP, VT, or MF is removed, Misery is also removed.