PVP is no match for /MA J. You can neither win nor loose anything. It's just boring. Barely anyone plays it. So maybe add that you can win random stuff by killing other players, like you can win stuff for clearing waves at ma j. The more players you kill before warping away or getting killed, the better the rewards.
If the player was to win a reward after each kill, it would be extremely easy for friends to farm kills off of each other. Also, this really only favors donors, as they have access to kits and /enchant. No support. If there is a better alternative to getting rewards suggested, I'll reconsider. Edit: I would suggest making PVP similar to arena, but instead of mobs it's teams of players. They could be the same kits from arena as well. This would help make the playing field more fair, as well as help limit farming.
