PvP

Starting from level 20, a lot of PvP options became avaiable. The penalty for dying is the same as PvE, you get an injury that you must get healed, otherwise your stats are decreased (depending on injury severity).

If you PK someone your name turns red, and everyone can attack you without fear of becoming red themselves. Guards attack you on sight too.

Duel
You can duel 1vs1 or party vs party. You can duel for "training" (the loosing side is left with a small amount of hp), and "for real" (the loosing side is killed for real, gets an injury and so on)

Warlord Arena
An arena you get teleported in, there's 1vs1, 2vs2, 3vs3 matches etc. When the queue is full for both parties you get teleported in.

You get Warlord points as reward, and you can buy titles with those. You lose points if you're defeated.

War of camps
This is a recurring worldwide PvP events. If enough people gets in the queue (5 each side) a battleground starts.

Hunt Arenas
A daily event that spawns rare tameable creatures, the catch is: everyone is red named there, so you either have to watch it out, or go crazy with free PK.

Worldwide PvP
Most world zones are free for PvP if both you and your opponent are level 20 or higher. The penalties are the same for general PK. You can buy wanted posters to get a prize on the pkers heads.