I think it would be cool to implement a challenge arena were a team of 5 would enter a zone (just normal shape like square pentagon whatever) and they would fight wave after wave of enemies (enemies seen in recent campaign lvls) and every round completed adds exp (no items... well i guess there could be on boss waves) . at the end when everyone dies, total exp/rounds completed would add up and divide the xp amongst the members. i think this would be a cool addition because it would add a lot of diversity and something for people to brag about (maybe in leader boards?)

please tell me what you think