This mob gets you into the various sewers instanced zones. Lair seems to be the most popular, because when you zone in, there's a very slight chance a named fly will be right at the entrance.
The named fly in LAIR is literally the first mob you would pull at the zone in. When you zone in, make a 90 degree turn to the right and the first mob you see closest to you is the mob that is a PH for the named.
If you have people who can invis themselves in your group, the best way to farm the loot off this named is to have everyone out of group, in a channel. Go to Gamesh and say "Lair"...he will give you an instanced zone. Then look at your map (assuming you have a map) and go zone in. Look at the PH, if it is a named fly, then call the rest of the group in. If it is NOT the named fly, just zone out by clicking the ladder and quit the expedition. Wait the 6 minutes to make a new request for an expedition, then go back to Goresh and say "lair" again. Oh, and ALT-Z opens the Expedition Window
You can invite people into your expedition from another zone by using the "/dzadd <playername>" command. Once they are in your expedition, they can zone in provided they were not in their own expedition at the time you invited them, then you can group up inside.
The Named mob in the instanced zone is called "Sludge-Eating Fly" ->
He dropped the vambs twice and the mask twice. The rest of his loot, like the INT caster loot doesn't seem to drop off the fly.
Anyway, this is a good way to get a few in your guild or even yourself some very nice items if you're a tank at least.