I dropped into The Hole at Master Yael and started clearing towards the undead city to get the Block of Black Ore from Lamenting Spirit for the Lost Koada`Dal Force quest. After killing a few elementals, a rat man, and several a rock golem, to my surprise, a "Block of Black Ore" dropped off the 5th a rock golem. No need to continue travelling all the way to top of the castle for some rare spawn!