not an rpg?
Why not just make the rpg and transform it into the pvp

The game just follows basic concept, its like pokemon. You train, you level, you final battle.
Ild rather have something more unique, instead of just leveling and killing, gets boring.
And with the boss drops, make a few more areas which are harder, part dungeon which allows you to gain items that are what moonfusion said, rare, godly etc.