Board Thread:Fun and Games/@comment-26295802-20160321234711/@comment-26453572-20160711160605

Olog-hai are said to know some black speech, but no Westron, which supports the enhanced intelligence.

Also, the Olog-hai originated from Dol Guldur (as stated in the appendicies), meaning the mod's Mirk-trolls are just Olog-hai.