A few friends have been knocking this idea around and asked me to submit it to the forums for consideration:

The Überena would be a new 4v4, 2v2, or 1v1 mode of PvP gameplay combining challenging PvE content with the existing PvP scoring system. In short, the Überena would be a progression of arena/DR/gauntlet-like rooms, the composition of which (layout/status/enemy theme/obstacles/etc.) would be randomized from room to room. Unlike gauntlet/DRs/arena levels, in which players have some idea of what will appear (at least in regard to the status and main enemy theme), players would have nothing to suggest the status/enemy theme prior to activating the party button, and would therefore have to be prepared for anything--there would be no option to change loadouts once a party button was activated.
Überena would have two modes: Speed and Endurance. Speed mode would pit competitors against one another for the completion of a set number of rooms (3, 5, or 10). Endurance mode would be a never-ending progression of rooms, with the match continuing until all of the players on one team had died. Like LD, part of the scoring of either mode would be determined by the amount of damage a team inflicted, however unlike LD, the other component of the scoring would be the relative amount of time taken for a match (speed mode would award points for a lower time, endurance for the number of rooms completed).
As a PvP mode of gameplay, the monsters in both versions of Überena would give NO DROPS (health caps, etc.), and players would only have their health from the beginning of the match with which to complete the match,* and the winning team would be awarded crs and rank points in addition to the chance for rewards for bribing Krogmo before the beginning of the match.
That's the idea in a nutshell. Please add your thoughts and suggestions, and +1 if this is something you would like to see in-game.

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*a note on the use of energy revs: all involved with putting this idea together agree that it would be best if there was no option for CE reving, especially in Endurance mode, however we also acknowledge that this idea wouldn't realistically be implemented without the option to spend energy in-game on bribes and reving (as per LD and BN). C'est la vie.