No one knows what has become of the ancient builders of the alien cities on the Targa Plateau! It is clear that they have been gone for sometime though, leaving the robotic Custodians and Guardians to watch over their legacy. In times of incursion, the massive Guardians awake, pulling free from their alcoves and stepping out to defend the city from intruders! Frozen over in a new ice age, the alien city has the chill of death lingering in the air and the halls echo with the sounds of the creatures that have started to take up residence there. A single new XL Enemy with two Targa Plateau Threat Cards for Damaged Guardians and three Epic Threat Cards including one calling for two Guardians.