I've used this patch when im using rAthena long time ago. I think its from eA if im correct and yes its bugged. I never tried the patch on herc. Never tried using @killable.
The condition should be that both parties are killable, with just using @killable, doesn't mean the other party/person has to be killable to kill the other person.
With the requested @pk here, you should be able to set PK conditions that count for every player I think.
Probably a bit like @duel? We might need more specifics ;p
Yes, My server is set to PK Mode.
Not like duel but, heres a situation. If player 1 is set to pk off and player 2 is set to pk on they cant hit each other just like @monsterignore but with players. Only the players who is set to pk on is hittable.