Idea for the Dev Team -
Create a raid dungeon with seven locked doors. To access any of the doors, you would need to find a key out in open world. After obtaining a key, you would have access to one of the doors which would lead to a Sin. You place key in Door and wait for the remaining additional players to use their key. You will be ported inside once enough keys have been placed.
Dungeon would be designed towards the Sin you are trying to overcome.
Strange dynamics could happen in these dungeons, for example, the Greed dungeon could be full of gold/gems/treasures all over the ground throughout - to the boss, however the more you pick up, the more fight penalty you place on your party.
A few other ideas:
Wrath - PVP mode is on
Envy - one amazing drop at the end of run, but only goes to one player leaving the others high and dry
Gluttony - dungeon full of potions and buffs, however, the more you ingest, the slower you become in your ability to attack. Though, you need some buffs to beat the dungeon, as it is tougher then most.
Boss drops are unique to the Sin you fought - both Cosmetics / Loot.
Basically, the point of the dungeons is that we as players need to overcome the sins within us and find a way to work together to accomplish the dungeon. If not, it will simply be mayhem and unachievable.
Anyway - thought it was a fun idea.
Thanks.