Nokkles' Comments

The best place to get him would be at Valguarde in Howling Fjord.  When I was farming for a Rare I had a level 25 as backup and two level 20-22.  I fought each spawn and by the time I had won the battle another spawn had popped up.  Just kept going until I got it.  Also, cycling through my lower level pets helped to get a few level ups too!

Best time to get him is defintely after a server reset.  The first week I had all the spawns to myself and only saw two Uncommons and no Rares.  Second week there were a few other campers and on my third fight I got a Rare.  Lucky!  Good luck to others!