Chapter 38: Entry Crystal and 'The Bridge'
Whenever powerful mana is felt in the surrounding, it could only mean two things, either a dangerous monster is present nearby and that mana is simply its aura, or a treasure exuding a dense amount of mana to the surroundings is nearby.
In the case of the former, other monsters would surely be running away from the source of the powerful mana. After all, if humans don't want to fight when all odds are against them, not to mention monsters. These cunning and dangerous beings are even more sensitive when it comes to picking who to fight. If they feel like they would definitely lose the battle, then they will not hesitate to run away.
As for the latter, it's similar to what is happening right now — monsters gathering in one place seemingly looking like they are forming a Monster Horde. Of course, there are also times when they are indeed doing that, but there are also times when a treasure is present.
