Just be aware how NPC Scan works and make sure you clear your cache before you start your campfest, in case you've seen its corpse in the past...

http://wow.curse.com/downloads/wow-a...s/npcscan.aspx

This addon doesn't use nameplates or mouseover units to find rares. Instead, it checks your creature cache for the moment a rare mob is found. There is one catch to this technique however: Once a mob is “found”, _NPCScan won't be able to find it again until your cache is cleared. If you find a rare mob's corpse—Dirkee for example—you would have to clear your cache before _NPCScan would find Dirkee again. Thankfully, clearing your cache is a safe and simple matter.
Clearing Your Cache

To clear your cache, follow these straightforward steps:

  1. Exit World of Warcraft.
  2. Delete the “Cache” sub-directory inside your World of Warcraft folder. For example on a standard Windows XP installation, you would delete the folder “C:\Program Files\World of Warcraft\Cache”.
    • Advanced users can delete “C:\Program Files\World of Warcraft\Cache\WDB\enUS\creaturecache.wdb” specifically to improve log-in times, where enUS is your language code.


Note: Windows Vista and Windows 7 users see this info if your cache isn't in the location above.
That's it. Log in after you've done that and you'd be able to find Dirkee a second time. It's completely safe because WoW will recreate your Cache folder after you log in again.