What [i]would[/i] be nice, is if the arena was like a 6 man team gets split into two, only to join up again at the end, all while still being able to talk and having to coordinate and interact with the other group. So for example, if we used Crota as an example for "horde mode", the 6 man team does the abyss together, fights that wave, but they get teleported to two identical bridges in different worlds in teams of 3. Then the three sync plates have to be activated (but not held) in the same order in both places to form the bridge, and fight that wave of ogres and wizards. Then both teams fight their own deathsinger, killing her at the same time, otherwise the one revives the other, and then fight through their own wave of knights etc. Then everyone gets teleported back to the same venue for the final boss as a 6 man team again. It'd be even cooler if one world was arc and the other was void, only to have it switch halfway through.