I was killing these when i was lvl 61 (necro) and would almost get an entire yellow every kill. Would scent of terris (resist debuff) then snare, and dot, while running along the trench. Once i got to a certain point, i would turn around, and run back, sit down and let pet beat it. It would take a good 8-10 minutes to kill one, but was worth it. Took all my mana to kill em though.
Of course, this was before they started summoning. Went on a vacation, came back 3 weeks later and went back to my routine, and got summoned about 40 seconds into the fight. Got stunned, and quadded for 500's twice while stunned... Needless to say i got owned. Thats what i get for not having FD up.... wish i had read the game updates before going after 'em again.

Bazu Blood
Bazu Bone
Bazu Plasma
Bazu Skin
Bazu Skull
Black Bees
Black Pearl
Black Sapphire
Bloodroot
Blue Diamond
Blue Flame Necklace
Celestine
Discordant Scoriae
Dust of Discord
Elaborate Defiant Breastplate
Elaborate Defiant Plate Vambraces
Emberflow Stone
Emerald
Excellent Animal Pelt
Excellent Silk
Excellent Spinneret Fluid
Fire Emerald
Fire Opal
Fused Loam
Harmonagate
Heavy Bazu Tongue
Hemic Marrow
Howlite
Kyanite
Legends of Norrath Starter Set
Malachite
Mossflow Stone
Opal
Partially Eaten Meal
Peridot
Platinum Etched Gear #1
Rhenium Ore
Ruby
Shroud of the Nimble
Slugworms
Sodalite
Star Ruby
Superb Animal Pelt
Trean Flies
Veil of the Windstrider