Since the Vex are associated with madness and time, the raid could involve one guardian having to choose between loot and the survival of their other guardians, or involve committing suicide in a Looper-esque scenario. Guardians might also be required to kill themselves or each other to find the correct route to an objective using the Ghost-vision death screen. Some sort of meld between PvE and PvP would be interesting. One method to prevent briefing during these situations could involve player-choice loot distribution, where each guardian would receive a key-buff, and they could choose from five urns in which to place the buff so that one of the other guardians could gain access to the rewards chest or something like that.