Overlord Against The Reapers

How would a raider know they had encountered a powerful monster? Well, there were always three clear signs. And depending on the intensity of each of them, battle with such monsters would be seen as suicide, not bravery.

First, the air would become suffocating. In the presence of an extremely powerful aura and dense mana, weaker life forms would feel an immense invisible weight bearing down on them, making breathing more difficult and their movements slower; at times, they may freeze up entirely.

Second, instinct. No matter how hard one may try, the body is always honest with itself, regardless of one's opinion or thoughts. In all living beings is engraved a single will: survival.

At times, it may be personal, or it might involve the need to sacrifice one's life for the continuation of others. Although there are many aspects of life it is involved in, instinct essentially exists to serve one purpose: to ensure the constant existence of life in the cosmos.