One surprise that has shown up, as far as something that was completely unexpected at this point, was the two battlefield additions to the rulebook that come with their own rules. The first of the Shrine of Aquila and the second, the Maunractorum. Lets take a quick look at the rules that now accompany these terrain pieces.
Please remember that these are still rumors, as we are getting closer to the rulebook release.
via an anonymous source on Faeit 212
This was unexpected, take a look at these.
Shrine of Aquila
Terrain Type: Ruins
the ruins are difficult terrain and all models inside receive a 4+ cover save regardless if they are 25% obscured.
Rules: Armies of the Imperium can re-roll failed morale checks if any models in their unit are inside the ruin. Any others get Hatred (armies of the imperium)
Manufactorum
Terrain Type: Ruins
the ruins are difficult terrain and all models inside receive a 4+ cover save regardless if they are 25% obscured.
Rules: Models in the Manufactorum that are firing weapons that have the "gets hot" rule, can re-roll failed saves from wounds inflicted with the Gets Hot rule.