Cain was also left with another issue. There was a large group of Beastkin here, who didn't know the war was over, or anything that had happened in the last two hundred years. Only one of them had a System interface that Cain has seen, and he hadn't even reached the first advancement.
They obviously couldn't be left alone here in the woods, but they would definitely freak out if he called a group of dragons to fly everyone back to the city.
"Would you all like to come to my house and we can catch up on everything that you've missed?" Cain suggests, and they all seem eager to get away from the place where they were imprisoned. Or perhaps it was because everything in the area was dead after being deprived of energy by the backlash of the spell.