After taking a little time trying to pick apart differnt mobs in the area to see what would be a PH here, what i have found is killing a giant diseased rat, a giant yellow recluse, a clockwork rebel, and rouge clockworks will spawn these little guys.
Edited, Feb 8th 2012 4:46am by FurtivoCarino

Bloodstone Ring
Brownie Brain
Brownie Leg
Brownie Parts
Brownie Torso
Carnelian
Coarse Silk
Complex Etched Rune
Complex Velium Embossed Rune
Crude Adept's Broom
Crude Adept's Mantle
Crude Binding Powder
Crude Combatant's Belt
Crude Combatant's Shoulderpads
Crude Defiant Amethyst
Crude Defiant Axe
Crude Defiant Breastplate
Crude Defiant Chain Boots
Crude Defiant Chain Bracer
Crude Defiant Chain Coif
Crude Defiant Chain Leggings
Crude Defiant Chain Sleeves
Crude Defiant Cloth Cap
Crude Defiant Cloth Pantaloons
Crude Defiant Cloth Sandals
Crude Defiant Club
Crude Defiant Emerald
Crude Defiant Fists
Crude Defiant Leather Cap
Crude Defiant Leather Sleeves
Crude Defiant Leather Trousers
Crude Defiant Plate Bracer
Crude Defiant Plate Gauntlets
Crude Defiant Plate Vambraces
Crude Defiant Shortsword
Crude Defiant Spiked Shield
Gold Painted Rune
Golden Earring
Iron Ore
Jasper
Mangled Animal Pelt
Onyx
Raw Crude Hide
Silver Earring
Silver Ring
Silvril Ore
Star Rose Quartz
Weak Gormar Venom
Weak Larkspur Extract
Weak Muscimol Extract
Weak Oleander Extract
Words of Possession

). There may be other mobs on this spawn table but not sure what (maybe Krags). Not sure if you have to keep the general mob population down to trigger this spawn table or just wait the 15-20 minutes reported elsewhere; I slaughtered just to be sure.