Overview[]
You can fight other players in the game to claim their gold. Zones where player killing is available will be in the dropdown with monsters -> you can switch to it players and hunt around for people.
Not all gems and gear work in PvP, so keep that in mind when choosing your targets! If you find yourself constantly getting PK'd, you can look to seeking refuge in a non-PK zone.
You can customize your kill message by using the command /pktag [text], but must have ":pk:" in it, which is your victim.
PK Range[]
You can only kill other players within your level range, which is your (Level +- (Level / 4)). For example, if you're level 500 then your PK range is 500-(500/4) to 500+(500/4) = 400 - 625.
PK Commands[]
You can view when you can kill again, along with your PK attack range, with the command /pk. If you have a timer, it'll tell you when you can kill again, and if not display "You are ready to kill!".
Rewards[]
For killing your opponent, you free them of any free levels (you do not get them though) and their gold (which you do get), a kill on the leaderboards, a 10-minute PK cooldown, and occasionally the player complaining in chat about you killing them repeatedly.
On top of that, you'll gain Alignment based on who you killed. If your opponent was neutral alignment, you'll gain -1. If they were 100+ alignment you'll gain -2 and +2 alignment if they were -100 or less.