Adreen appeared during a meeting of the High Lords during the early stages of the Siege of Terra. During the meeting he cracked a joke that Horus would be easier to beat if had lost his mind. The joke drew a chorus of laughter from the other High Lords, but Malcador and Rogal Dorn were silent.
- 1: The Siege of Terra Continues (last accessed 3 July 2019)
- 2: The Lost and the Damned (Novel) - Chapter 23