From the announcement:
Hail Survivors! Announcing the Friends and Foes Optional Buy for Zombicide: Green Horde. This is a full expansion that will enrich your Zombicide adventure. Friends and Foes adds new Survivors and faithful Familiars, but they will have to face off against Tainted Walkers and an Abomination. This expansion also includes five new double-sided landscape tiles and 10 new challenging quests! For the Green Horde!
The campaign continues to chug along with still 21 days left to go.