This is basically a map that can be available in 1 or multiple channels and cost money (example 20mil) for each participant to enter. -You and the participants get teleported to some random look alike map in the game. (example Helios Tower Entrance) -You fight a random boss (or random bosses) that don't drop items/exp, or they can depending on which path is better. For example you and your friends pay to get in and you fight Pianus under water (so you take drowning damage and float), Horntail head in El Nath (take cold damage and slip), Zakum Body + black crow or Toad boss + Bodyguard A+ Mano. The bosses can also be a bit different than their counter parts like maybe you fight vs Anego that uses speed and defense up, Papalatus that does double damage or krexel that poisons. The maps, bosses, and added stats do not have to be random they can be customized by who ever does that stuff and given a 1-??? list of challenges for people to pay to take on. These would just be end game fun challenges they do not have to give items/exp (maybe) or have a surplus of channels for.
I like your idea, but I'm not sure that people would actually pay to use potions on a boss with no exp or drop return.
That's more like a CPQ thing where you pick up potions and fight bosses going up the level. My suggestion can pit you against a combination of bosses in a not so friendly map. I mean it can or can't give drops I just personally don't know how everyone feels about bosses you pay to fight that drop the same items as the originals since people want to focus on balance so much.