During this past WvW reset, I brought out my (newly level 80) thief so I can get away from the usual hammer train shenanigans, and back into an anti-peripheral role. But, what exactly does anti-periphery even mean? I throw the term around quite a bit, but I realize that it's kind of a specialized term that not everyone may fully understand. I've described it as "staying to the outside of battle and attacking squishies", but that explanation does not do it any justice. So, let's dive a little bit deeper into what the ant-periphery role entails.
First, outside of the initial might stack, you are typically running on your own, "doing your own thing", if you will. You need to be mindful of where both hammer trains are, but you do not stick to the hammer train. Your goal is slightly different from usual. You're not trying to DPS large groups, like a staff ele or necro would. Instead, your goal is to a) prevent the classes that stick to the periphery (the outside) of the fight from being able to participate in the fight, and b) punish those classes that come from the main hammer train to the outside of the fight to heal or wait on cooldowns.
"So, does that mean I need to pick a target and DPS it down, and then finish it?" Not exactly. It's great if you can DPS a target down, and even better if you can finish them, but by no means is that necessary. Just attacking an enemy can take them out of the fight, or waste cooldowns, due to having to defend themselves. And if you down an enemy, but leave them (e.g., if it is unsafe to finish them), then that potentially takes even more enemies (temporarily) out of the battle to resurrect that downed enemy.
As well, just providing support for those around you is also useful. If you can blind a downed enemy that another player is finishing, that could help the finish to be completed safely (especially if they are finishing a downed guardian). This is why in the video below you will notice that I drop a Black Powder on top of any downed enemies that I come across (or that I down myself and leave for others to finish).
Because you are essentially "in your own little world" while running anti-periphery, I cannot stress enough how important it is that you are aware of your surroundings, pick your targets carefully, and do not over-commit to your target. There are a number of examples in the video below where I will begin to attack an enemy, but will disengage when the situation becomes (potentially) too dangerous. In terms of being aware of your surroundings, there is an example in the video below where I am down to only a few hundred life, but continue to engage an enemy who is running up the stairs--it ends up that we both get downed in the encounter, but because I was aware that the friendly hammer train was on the wall somewhere at the top of the stairs, I knew that even if I got downed, I would likely end up rallying after the exchange.
So, to sum up, when you are running in an anti-peripheral role, you are running in conjunction with the hammer train, but outside of it. You assist in many ways, while keeping your distance from the main trains (both friendly and enemy trains). You punish players that stray too far from the safety of their trains, placing precedence on squishier or low health targets. And you survive. You pay attention, and survive!
Normally if running this style of play I bring out my mesmer, but I would like to get used to my thief, so yeah. With that said, I found that I was really not taking advantage of a lot of the tools that the thief brings to the table (Steal and stealth/backstab, mainly), but it was still a great night. I recorded the entire night, and made a little video to showcase some of the fun. Keep in mind that the video is more so showcasing the anti-peripheral role, as opposed to showcasing my mad pro thief skills (...because I do not, yet, have mad pro thief skills :P).
[WARNING: Explicit language used in the music for the following video.]