- A repository of occult knowledge built by the Thousand Sons to house their myriads of tomes and scrolls. - Contains many researches that improve the effectiveness and spellcasting potential of Thousand Sons psykers. - It is a place where special magical artifacts and enchanted arsenal can be acquired. - Projects a control aura about itself in which other structures may be built. - Returns a small amount of the initial invested resources, once built. - Limit of 2 Dark Libraries per Thousand Sons army deployment. - Magical Studies: Near the Dark Library the spell and ability recharge time flows faster for all casters.