I've just killed this for the second time on my 53 Bard (nerf bards). First time he dropped the mask, and the aug the second time. He was yellow to me, if that's helps in trying to work out the level range.
It -might- range from 55-56, but the one that I saw was yellow to 55, even to 56.
Dropped
Crystallized Griffon Eye MAGIC ITEM LORE ITEM NO TRADE AUGMENTATION This Augmentation fits in slot types: 7 MANA: +30 Endurance: +30
Restrictions - Slot: EAR HEAD FACE NECK SHOULDERS ARMS BACK WRIST RANGE HANDS PRIMARY SECONDARY FINGERS CHEST LEGS FEET WAIST Recommended level of 55. Required level of 48. Class: ALL Race: ALL
Item Information: You must use the solvent Class XIII Augmentation Distiller to remove this augment safely.