Here is what is in the new Codex: Imperial Agents
Inquisition, Officio Assassinorum, Deathwatch, Grey Knights, Adepta Sororitas, Cult Mechanicus, Adeptus Astra Telepathica, Aeronautica Imperialis, and the Legion of the Damned are all confirmed as part of Codex Imperial Agents.
via Warhammer Community
https://www.warhammer-community.com/2016/12/05/no-one-suspects-the/
With the arrival of Daemon Primarchs into the galaxy and traitors spilling from the Eye, the Imperium desperately needs to work together to ensure its continued survival.
Next week, they get much needed aid, in the form of Codex: Imperial Agents.
This is a book that compiles together loads of specialist forces that commonly operate alongside other armies within the Imperium – including agents from the Inquisition, Officio Assassinorum, Deathwatch, Grey Knights, Adepta Sororitas, Cult Mechanicus, Adeptus Astra Telepathica, Aeronautica Imperialis, and even the Legion of the Damned.
Much of this content is only available digitally at the moment, some of it is new, and much of it is updated.
It’s worth saying that this will not replace existing printed codexes for the Deathwatch or Grey Knights – this just means that, if you want to add a small strike force of Elite Space Marines to your Imperial army (perhaps requisitioned by an Inquisitor, or high ranking officer), this book makes it easy for you to do so.
Speaking of which, one of the coolest things in the codex is a change to the way that the Inquisitorial Henchman Warband works. To further represent the unique nature of the Ordos (and a lot of the fiction featuring these mysterious individuals) Inquisitors can now go to battle with a squad of elite power-armoured warriors appropriate to their specialisation: Grey Knights for the Ordo Malleus, Deathwatch for the Ordo Xenos or Battle Sisters for the Ordo Hereticus, they still keep their acolytes, general hangers-on and space-oranguatan-mechanics.