Craftland.org

An arena where players can choose to fight multiple bosses at once. Players can go to /warp DungeonArena (or something) and be greeted with an interface where you choose to fight multiple bosses. Say the said player chooses Ocelot Boss, Slider, Wither, and Sun God. They click an "O.K." button and are transported into one of many arenas. Each boss spawns in 5 second time periods and all aggro on the player at the same time. If the player wins, he gets some sort of prize dependant on how many bosses he spawned, and off of a percent chance for getting good loot.

Great idea blue There could be a hat with all the bosses on it (very small bosses models on hat). You obtain this hat if you killed every boss in game in one match.

I can see flaws:

-This arena could possibly downgrade ./arena
-This arena could possibly downgrade other boss chambers like Gold Dungeons
-This arena could produce lag due to some player wanting all the bosses on him.
-Pretty sure having a Cat + Wither + ect. would make it so OP and wouldn't be worth trying unless you wanted to break your armor

Pretty much this idea I can see going very wrong the way it is mentioned in your suggestion. If there was changes to the mechanics and how things worked and ect. then maybe (very small maybe imo), But yeah i wouldn't support.