I like the gambling idea. Firstly, the classes could work like the old mobarena, Dannie knows about this. But, I think you guys are looking for something differenty, new idea!
Let's say two people hated each other? They set up an official arena match.
-An admin would need to be online to make it official
-A time would be set
-Both players can bring as much of their shit as they want, they have to use their own gear and food.
-People can come and bet diamonds to the admin, double or nothing.
-The winner gets all of the losers loot (And maybe the diamonds that people bet against them, helping underdogs to earn more?)
Scenario:
Dannie and Ollie decide to book an arena match and Aggravate is online.
Aggravate teleports them to the arena when they're ready, Jpev and smokles go to watch, smokles bets 10 diamonds on Dannie, Jpev bets 10 diamonds on Ollie, they give the diamonds to Aggravate.
Dannie slays Ollie and picks up all of his stuff.
Aggravate gives Smokles 20 diamonds back for being a bro, Jpev gets nothing.
Aggravate then gives Dannie the 10 diamonds that Jpev bet.
-Players get to gamble and watch PvP
-People are rewarded with mega diamond from the people who doubted them.
-PvP action for all