Hello there
I've found an elite mob in the Townlong Steppes that often spawns 4 ghosts, the ghost die after some time and you gain 10*4 rep (without guild perk) for the black prince.
So basically you just stand there and get around 40 rep within 30 sec. But you need an AutoItScript or something similar that let's you repeatedly press one button.
The mobs don't do a lot of damage so I had one rejuvenation every 5 sec or so.
Elite Mob: Shan'ze Illusionist - NPC - World of Warcraft
Spell: Spirit Split - Spell - World of Warcraft
Adds: Spirit Fragment - NPC - World of Warcraft
Location: