Been keeping track of drops over the last couple months. In addition to the above, this mob also drops:
Part of Yaeth's Compendium Pg. 26 (Left) Rune of Association Rune of Coruscating Rune of Tempest Steel Ch'Ror Steel Re'Stek Words of Capacity Words of Revenant Words of Virtue Yaeth's Compendium Pg. 113
My lvl 55 Bard was landing slow on these guys about 40% of the time. They were a red con of course. When I used the "tash" song which lowered MR by about 25 I could land it about 60% of the time. So their resists aren't too bad I guess. Especially if they don't con red to you I bet :P
They cast (as their name suggests) and they hit hard and fast too. They can dot and are pretty nasty.