The Children of Nightmare indeed had no intention of ambushing; after leaving the town, they headed straight for the ancient arena fortress of Biggs. When they had traveled to within a few dozen kilometers from the ancient arena, they received a message from Biggs saying that the Children of Nightmare had arrived and were preparing to attack the fortress.
In the ancient arena, Biggs looked gravely at the many Children of Nightmare amidst the ruins outside. The place had once been teeming with the Undead, which had now been slaughtered, and any occasional respawns were immediately killed.
The number of Children of Nightmare was beyond his expectations, but fortunately, they had anticipated this, and there were over a dozen companions with him at this location.
Although their numbers were far fewer than the Children of Nightmare, early defense wasn't a problem.