According to Langrum's master, Calirer, the abyss goes through cycles of intensity in its laws. Only those with demon blood can survive there, but during a cycle every ten years, the laws reach their lowest intensity, allowing other races to enter. This cycle finally arrived, but it was still by no means safe. (Chapter 173)
The Bloodthirsty Light Sect had two black towers at its disposal, but descending into the abyss was dangerous even for the patriarch. Dividing their forces would leave the disciples and even the elders vulnerable. According to Almin, the three sects used only one tower each, entering all from the same sect, in the quest for survival in the first region.
