- Commander Unit (Secondary). - Boosts morale recovery when attached to squads. - Psychic unit with many powerful abilities focused on weakening enemy resolve. - Effective against Infantry, Heavy Infantry, and Daemons. Excels at close combat. - Librarians are Space Marine psykers. They fulfill several important specialist roles in a Chapter: off the battlefield they are responsible for interstellar psychic communications. In battle they utilise their abilities as powerful psykers. They are among the most knowledgeable of the Chapter's history and traditions. According to the guidelines of the Codex Astartes, the armour of Librarians is blue with gold and yellow highlights, regardless of Chapter's colours.