This is an idea i had from somewhere else.
The Oryx Arena was like the solo arena we have in nexus, with waves and bosses,
however the bosses dropped the loot directly from them when they died, and everyone could join at once, and be in the same arena.
This arena could be opened by a universal item such as the Wine Cellar Incantation, however it would be much more rare/expensive, with the unlocker being preferably soulbound.
It could also be bought from the nexus, to increase income for Deca, which would allow them to keep the servers running (not like they get enough money as it is)
Also, certain bosses like Void entity in higher rounds could be included, which would encourage classes like paladins and priests to join the arena aswell.