See this came to mind when I saw a guy temporarily quit his guild to pvp with his mates because of guildmates not being able to attack eachother in the woods. Now, what if we had an area off the main path of the forest (Like how the pit is seperated from the main path), where it's literally just normal pvp but guildmates can kill eachother. Of course there should be two NPCs telling you the purpose of said area, something like "these are the rogue's palms, where comradery is a fairytale" or whatever other way you can say "guilds don't work in here".
In terms of theming I guess you could have it be the literal opposite of the pit, where instead of going down a pit, you climb up to the top of a tree or something, I dunno. The important part is to make it clear to the players that the area does not work with guilds, and have it be harder to enter than the main path. All else is just part of basic pvp, ya die and ya drop your coins, yadda yadda, whatevs. I think it would solve some mild inconveniences for guild members trynna spar and just overall be a new interesting world addition, so unless there's something wrong about this suggestion I think it'd be neat.
Rogue Forbidden woods area
WELCOME TO THE AGE
OF THE CEBINAE!!!1111
OF THE CEBINAE!!!1111