So youll have an orb (or buy it, unlock it, anything), which can store xp.
It would work like a bank, but it stores experience, you can deposit your xp, withdraw it, or make it take a part of your xp if u get some. This way, ppl who want to farm but not want to lvl up can just deposit the unneeded xp, but when needed (new set) you can just take xp you earned(youll have to take as much as the lvl up needs because thats how the current xp system works).
But this was the single player part, you can give this xp for others for tickets/coins/beign_extremly_kind etc.