"Lowlifescum" over on the official WoW forums has had an interesting idea, to combine PvE instances and Battleground instances into a kind of "race-to-the-boss" PvP and PvE experience combined. According to someone’s idea, players would queue up for the instance, and when both 5-man teams are ready, begin on opposite ends of a dungeon. From there, they have to fight their way through normal monsters and 1 or 2 regular bosses before finally reaching the final boss in the middle. They would have to choose between rushing through as quickly as possible in order to reach the final boss first, or else moving slowly and steadily enough that they can avoid setbacks along the way, and arrive at the last boss fully prepared for the other team to attack in the middle of the fight.

    The first existing instance your mind jumps to is likely Alterac Valley, but this new instance would be different in that the players are not marching towards two separate goals, split up into two offensive and defensive groups, but rather going after the very same bosses and getting in each others way to a certain extent. Obviously it would also be a lot smaller than AV too, and, like Arenas, based from the beginning on teamwork with your friends rather than random groupings of strangers.

    Obviously balancing such a battle would be very difficult, and the losers should feel as though they gain something of value even if they don't beat the other team. When imagining this sort of instance, players mey envision something like a maze where players can not only meet up at the last boss, but also sneak around and PvP with each other the whole way through. Different sections of the instance could be designed to provide advantages to different sorts of classes, whether melee or ranged, damage or healing, and monsters could be designed to interact with the two groups of players in some very dynamic ways. Perhaps the bosses and maps could even vary a bit from battle to battle to keep everything fresh.

    A Blizzard representative showed up in the original thread to say that he liked the idea too, and hopes that someday we might be able to see something like it.

    A central room *thinks The Maul* with arena-pvp-flag. Then two seperate instances leading from there, each boss seperated by a door. And each time a group has cleared a part of their wing, a yell alerts the second group to their position. Ofc the boss should be a random spawn :)

    That would become a huge race. It's profitable to arrive way before the second group, so you can kill the boss and have time to regent a bit before the PvP starts. But it's also profitable to clear you wing just a little slower than the second group, so you can bustle in when they're occupied with the boss.

    Nail the tank, the boss wil do the rest for ya. Nail the healer and you're in for some fun too.

    But of course we should have at least 2 instances that work like this! 1 for 5vs5, the other for 10v10. Or worse. A version with multiple wings (think 5+) and everyone gets his own random wing, with a max of like 4 groups of 5/10 people.

    Perhaps make it so that you take some sort of resource which will assist you in either the PvP battle or the mob fights battle. Then you have a choice as to whether to use these reources to get to the boss quicker (and thus have less at the PvP battle) or save the resource and get to the boss slower (thus having more for the PvP battle). In this way, neither team will know exactly what type of advantage it has when they meet up.