Killax of Shadowsong (US-A) was dueling some of his Horde friends in the Dalaran sewers, for some ungodly reason, when he was feared through a wall into an empty arena. His blood elf pal blinked to follow him, and wound up in the same location. Suddenly, a draenei shaman and a blood elf warlock spawned before them, and proceeded to do battle under their respective flags. I wonder what else the NPCs get up to when they think we're not watching? It might be best if we never know.