Please explain the mechanics of PVP in this game.

Spirit would be the answer. To put it into perspective, that player in the middle of all those R9 +12s, can choose to take his entire gear set off, and still not die if the Spirit gap between him and each one of his 30 theoretical attackers is still larger than 2000+ by some means.

Well each player no matter the class has available to them, a genie skill that gives them invulnerability for a few seconds, and apothecary that gives them invulnerability for 12 seconds. So any class has at least 16 seconds of invulnerability, couple that with spark your up to 18 seconds.

Now each class has some sort of defensive perk, for instance pyschics can go immune to psychical dmg for so many seconds, barbs can get 90% dmg reduction for 20 seconds, plus another 60% dmg reduction on a genie skill for 10 seconds.

So you get the picture. Taking down a target can often be a battle of attrition + teamwork. Harken back to the old days when lunar bow archers, then rank nine would one shot half of your faction.

If someone is trying to obtain an objective when fighting, or don't know they have to be ready to tank, or have skills on cooldown, or caught off guard, they will die much easier.

With a variety of classes targeting one guy, he will not be able to accomplish much in general, and on average die in under 30 seconds.