"Got me there," Blaze chuckles. She picks out an open door at the side of the plaza to head for, one marked by a serpent-twined rod painted in green on a white cross. All the important signs here are trilingual: just inside the door, green lettering on the wall assures them there's a medical station down the short ramp, repeating in Portuguese and Chinese.

"Every few decades, I think. The Fallen are always testing our defenses. It's been a while since we've had a sustained assault, but there's still no safe ground past the Wall. One of our tasks is to keep our enemies too fractured to co-ordinate another threat like that."