I thought of an idea, just basic, and what the name implies. (Rushing every boss in a world) There would be a tower, with every boss, no drops, no wisps, no minions. Each floor would have a different boss in that world, in a chronological quest-wise order. However, before you call me crazy, each tower has bosses ONLY from that world. So it would be: Wizardly Sanctum Krokotopian Sanctum Marleybonian Sanctum Mooshu's Sanction Dragonspyre Dungeon Celestial Sanctum Zafarian Sanctum Avalon Castle Aztecan Asteroid There would be a quest giver that would allow you into the rooms with the instances, as to not spoil it of course.
Where would this be? Underneath Ravenwood, held up by Bartelby's Roots!