It appears that there is a new mission for Betrayal of Calth that includes Daemons now. Also a new mision for bringing in a Daemon Prince for Executioner Force. Here is what is new, and of course a link where you can find the latest leaked information.
Betrayal at Calth Exclusive Mission- Scenario VII- Rise
Assassinorum Daemonicus
via Atia on Bolter and Chainsword
http://www.bolterandchainsword.com/topic/317262-new-bac-mission-new-assassins-game-rules-battle-brothers/?p=4254887