Large scale open RvR is a beast onto itself. It encompasses everything from simple individual efforts (appropriate damage dealing, healing, damage soaking et al), to more group oriented actions (moving as a unit, following the assist train on targets), up to warband level goals (suppression, zones of control, distributed control efforts) and beyond (multi-warband cooperative effort). Let's look a little at what goes into large scale open RvR in Warhammer...
However, not everything mentioned above is required for open RvR fun. Heck, it's not even required to succeed most of the time, but it's
there as an option to bring about more tactical and strategic play. And it's all down to the players on both sides of the war.
On the individual level Warhammer has done quite a good job of making almost every career and every mastery path worthwhile to some extent. Especially as you're not hindering anyone else in participating (there are no unit limits outside of the effect on performance), even if you're specced to deal damage as a zealot, at least you're not a burden.
That being said, there is a sliding transition from being "present" to being "useful" to being "feared" on the battlefield, and it is easier to excel in this regard if you're playing to your careers core strengths and gearing appropriately. Remember that everyone but ranged damage dealers are guaranteed to take damage (ranged damage dealers just take un-guaranteed damage), as a witch elf you might be tempted to stack gear that increases your damage, but if you're healers can't keep you alive, your theoretical damage output while alive is fairly irrelevant. Never forget that your effect on the battlefield, while dead, is zero.
Moving onto the group level things change a bit. Quite often in open RvR you won't have a fixed group that supports you and you'll have to deal with random people in your group. In these cases it's important to try play consistently and communicate. You have a party chat for your warband (/wp) and using that to inform people of your actions might be useful, if they're the communicative sort. Operating as a group can be devastating, a well-organized assist train that flanks the enemy to get to the squishy healers can quickly break the back of a full warband.
However, it is worth thinking of how your party is set up. If you don't have a healer, you're not going to be much use on your own. If you don't have burst damage dealers or some stellar coordination with crowd control, you're not going to sink a few healers working together. See what you have, and decide what role you can play. This is a great situation for a group of guild mates to form a unit within a warband.
On the warband level it can either be "one big mess of people whacking at another mess of people" or you can run into the truly organized ones. The warband that has a clear leader and groups set up for specific purposes. If you're in one of these warbands, you'll notice it quickly enough -- there are orders and communication. Try to lean back for a second and take in the general idea of what's going on. If the warband seems chaotic, see if you can tease your group into being more active, or, optionally, just ignore tactics and whaaaaaag at the enemy. In the right doses whacky crazy zergfests can give you quite a lot of fun anyway.
Of course, in Warhammer, sometimes you'll need more than one warband. Sometimes you're looking to lock down a zone and you want lots of people, everywhere in the zone, working together. Suddenly /1 becomes your command channel, and your warband becomes just another unit. If
you're not leading these situations, it's often best to either go with the flow (or zerg, depending on your point of view) or listen for requests (people will often ask for reinforcements to specific places). Listen and if required talk to your party and warband so you're all on the same ball. Spreading out is bad, even good addons for healing and res overview (like squared), can't magically reach across the battlefield.
Anyway, give open RvR some thought, if you feel like it. To enjoy Warhammers huge RvR world, you're not required to go into every war behaving like a four-star general, but it can bring about some really amazing moments as a small group of you suddenly break and entire warband.
But above all, have fun. And help those around you to have fun. If they're zerging without any real plan, don't try to herd cats. If they're trying to take that fort, try to assist as best you can. But don't sweat it too much, the War goes on. And on. And that's just how we want it!
