Dueling (adapted from the EQ ruleset for dueling)
Create a /duel command which does not restrict PvP interaction in relation to levels--all levels can /duel each other. Consider this more of a roleplay command (where people can settle a score or dispute one-on-one) than it is a PvP command, but obviously, it can be used effectively by both RPer and PvPer alike.
No other players can interfer in any way with two people dueling (can't heal, buff, assist or attack either dueler) if the duel is held outside of a 0% suppression gas area. A duel can not be initiated if both individuals are in a team together. Titles can not be gained through dueling. XP/SK can be lost (and placed in one's XP/SK pool) through dying in a duel if one does not save prior to the duel.
The winner of the duel is determined by one thing: whomever remains last in the playfield where the duel was initiated--either by not running away and zoning, by not dying, by not going LD or logging off. (A playfield message giving the results of the winner and loser would be a nice touch.)
However, guards will not tolerate this type of behaviour around them and will respond accordingly--if two people think they want to have it out right next to guards in the middle of a city, the guards will attack them (or at least the initiator of the attack). To limit the potential for disruption, it will be impossible to /duel in an area which is 100% suppression gas. This would unfortunately limit some of the RP dueling within some clubs (Rompa's does have a 75% gas area...in the women's bathroom ) but ensure that social environments don't end up being invasive PvP dueling free-for-alls and disrupting the environment. Perhaps make a room in Reets and other clubs 75% gas to accomodate /dueling.
(And don't use the shortcut of /d unless you want people responding to rude and demanding 'newbie beggers' with, "Sure, just type /d to open up the donate window." )