Been keeping track of loot for the past couple months. This mob drops:
Dragon Boneshard Part of Yaeth's Compendium Pg. 118 (Left) Rune of Association Rune of Complexity Rune of Coruscating Rune of Incitation Rune of Tempest Steel Ch'Ror Steel Re'Stek Words of Abrogation Words of Capacity Words of Immunity Words of Misery Words of Revenant Words of Virtue Yaeth's Compendium Pg. 113 Yaeth's Compendium Pg. 115 Part of Yaeth's Compendium Pg. 26 (Left)
Casts shaman type spells, Malosi - Torrent of Poison (ae poison spell). Not many HPs but hits upwards of 300 sometimes. Very disease and poison resistant. Edit: Forgot to mention that when trying to cast pacify on these guys, it says "Target unaffected".