PVP, protection style
One of the things that's improved prot's on-demand damage potential significantly is the unlinking of Recklessness and Retaliation from stances. Speaking purely for myself, being able to charge into someone and then pop a Reck/Shield Slam macro makes my day. In a full set of PVP gear, you can have fairly respectable critical hit chance and do some decent damage all around. Using Colossus Smash most effectively with prot still requires either a quick hand at stance switching or a macro, but it's worth mentioning for boosting that on-demand damage.
While prot can hit respectably in PVP, if you're playing as protection in player vs. player combat and you're wanting to do monster damage, you've picked the wrong spec. The trade-off here is twofold: You lose the high burst damage of the other specs (and even their overall sustained damage) and get survival and utility in trade. In Arena play, I use protection to harass a caster, especially a healer. Between Gag Order, Shockwave, Spell Reflection, Intervene and a variety of survival cooldowns (Shield Block to reduce incoming magic damage, Shield Wall and Last Stand to preserve your own life), protection can be both an absolute pain in the behindus to kill and an even larger rear-end briar to have on someone you'd rather be free to act. Properly played, a prot warrior can stun an entire 5-man Arena team at a key moment, preferably when the rest of your group has picked a target to unload on.
Outside of Arenas, in BG play or world PVP encounters like Tol Barad, protection can serve as an excellent flag return, a very good force in the scrum for flag capture and even better at preventing flag capture and holding an objective in AV or AB. Of course in cases where something needs to be tanked (both Isle of Conquest and Alterac Valley present such), protection does that job as well as it ever has. This is where keeping your PVE tank set close to hand and ready to switch into comes in handy. Or if you're gonna be fighting a rogue and you want some laughs. In general, I prefer keeping my resilience set for most actual players, though.
I find myself using different sets of gear for prot PVP depending on what I find myself facing and what I plan to be doing. In an Arena match or when flag running, I tend to want to go for resilience, and so I wear standard PVP gear (although I don't have the PVP shield or a PVP one-handed weapon), while if I'm going to be tanking or holding an objective one-on-one I'll sometimes wear PVE tanking gear instead, sacrificing resilience (which does nothing against, say, Vandar in AV) for dodge and mastery (both of which do).
PVP gearing for protection
In general, PVP gearing isn't any great mystery for protection. Mastery in general's a lot stronger for prot spec than for either arms or fury, so I definitely recommend holding on to as much mastery on the PVP pieces you pick up as you can (getting options for a mastery neck, cape, bracer, etc. is definitely worth considering) without skimping on offensive stats like crit.
It's tempting to wear more PVE gear in PVP for high dodge, stamina, and mastery for block but don't skimp on resilience; 95% of the time, you'll be better off. Resilience affects magic damage from enemy players, and magic damage bypasses armor, making it one of any warrior's worst nightmares. Even with the ability to reflect spell damage and reduce incoming magic via Shield Block, resilience can and will save your life when a mage opens up on you from the throng of enemies.
You don't really need
a PVE set at all to PVP as prot. The bosses you'll have to tank to win PVP Battlegrounds are designed to be tankable by tanks in PVP gear. It'll be easier to tank them in PVE gear; I can tank Van and four warmasters in my PVE set if the healers are awake. But it's doable in PVP gear.
PVP basics for the prot spec
You can use your basic PVE tank spec for PVP pretty easily, but it's also possible to tailor your protection spec for PVP. I tend to glyph for Intervene
, for instance, because I like being able to tank enemy attacks for vulnerable teammates, especially if I feel comfortable in using Spell Reflection right after. Likewise, I really like Gag Order for PVP, as being able to silence an enemy from range if I can't get out of being kited immediately is a nice bonus. Other players might prefer Impending Victory for more self-healing and a glyph of Victory Rush to go along with it.
changes to the various talent trees didn't trim protection as much as other specs; in the end, prot ended up with more really nice talents than you could really take and still branch out into other trees, meaning that the PVP prot warrior can sit down and really customize his or her talents based on what she or her is expecting to do or wants to specialize in. Someone who expects to do a lot of flag carrying might want to glyph Shield Wall and pick up Last Stand to boost the ability to weather focus fire from groups trying to stop a return. If you'd rather focus on Heroic Strike instead of Shield Slam, Incite might be attractive.
in particular is one of those abilities that I think a lot of warriors in general tend to overlook, especially in PVP. For a protection warrior, Intervene gives you a bit of your tankishness back against players. It's a lot easier to use with a focus macro, as targeting an ally on the fly can take time you'll want to have to get a Spell Reflect or Shield Block/Wall off once you Intervene and eat the attack meant for them. If you have ever managed to Intervene and then SR a Polymorph onto a mage, you'll know how awesome Intervene can be in PVP, and I recommend practicing its use.
PVP and Vengeance
Vengeance in PVP is something that's there and certainly can help you as a prot warrior, but in general it will really only come into play in situations where you're taking a lot of damage and being healed up. I mostly find it useful when I'm being attacked while carrying a flag or defending an objective. It certainly doesn't make you an unstoppable PVP juggernaut, as most of the time it falls off quickly and really only stacks appreciably when you're taking sustained heavy damage. I have yet to be in a situation in either an Arena or in group PVP where people thought the prot warrior was the best choice to burn down before anyone else, but maybe someday I'll get that mythically stupid group and get my attack power up to ludicrous levels.
I did once manage to hit Retaliation with a high stack of Vengeance while guarding a tower in AV and watched a DK kill himself hitting me. Once.
In general, prot is a lovely PVP spec as long as you're willing to accept the inherent trade-off of playing a tank spec with reduced offense but a lot of tools for mobility, caster harassment, flag return and objective control.
Next week, probably armor sets again, and by the time the PVP series rolls around again, I will have had time to try arms out again.
Read: PVP with a PVE spec -- fury
At the center of the fury of battle stand the warriors: protection, arms and fury. Check out more strategies and tips especially for warriors, including Cataclysm 101 for DPS warriors, a guide to new reputation gear for warriors, and a look back at six years of warrior trends.