From the announcement:
Today I am very excited to be bringing you 2 new armies from Grimdark Future and Age of Fantasy, both of which are very unique:
The Titan Lords are interesting because all of their units are titans which pack some incredibly heavy weapons. They can either be taken as a stand alone army or as extra units for your existing army.
The Rift Daemons are a great addition because they are are integral part of the Age of Fantasy lore, so it’s great to be able to field this existential threat on the battlefield.