The so-called "positive" change is merely that superficially it does not cause severe mutations in the body, but may still grant creatures different abilities.
For instance, humans who absorb large amounts of Abyss Energy could possibly grow wings and fly through the sky.
Of course, this mutation does not exist in isolation; when wings grow, changes in bones and skin might bring other side effects.
Such as a mutation in the whole body's skin, leading to varying degrees of allergic reactions, or even reddening and ulceration just from contact with air and sunlight.
This kind of mutation is similar to human gene mutation, which also has "positive" aspects; however, the probability of such is very low.
The vast majority of humans end up mutating into various terrifying abnormal bodies after absorbing Abyss Energy.
Such mutations include bodies covered in tumors, or bone endings that grow infinitely, or entire skin turning mucous, degenerating into soft-bodied monsters.
