It seems to be a pretty rare pet. I believe there are only 6 on my server and I have one of them.
If you do not know what it is:
In the cave on the bottom right of the DMF Island map there is a rare spawn level 93 Darkmoon Rabbit. It will randomly latch onto an enemy and fear it out of the cave while killing it. It's kinda hard to survive, you need something like a BoP to survive it. I've managed to survive by Ice Blocking some how. When it dies it drops 1 epic pet, the Darkmoon Rabbit.
The pet is basically the snowshoe rabbit with a bloodied face. The whole thing is supposed to be a reference to Monty Python and the Holy Grail.
The respawn timer is not only unknown, but is also speculated to have a special condition.
I've killed the boss four times and won one pet (legitly mind you, careful of ninjas; remember loot rules).
This requires around a 30 man raid minimum.
It has 174mil health.
Due to it being level 93 you will miss it OFTEN.
So why isn't anyone discussing it is my question I suppose. No discussing spawn rate/condition, selling, farming, etc?
It should be noted that I believe cross realm zones affect this spawn.
EDIT: I realize there are "guides" on it, that's not what I'm trying to do here. I was contemplating discussions about rates, special condition, and hell you could talk about the Monty Python references.