While Cliff, a 27 year old young man, was visiting his grandparents, he was caught in what is called a "summoning" which took him to a forest infested with unknown creatures, he decided that in order to survive, he should be ready to brave all the dangers that would present to him, with his “drain” skill he would fight them to become stronger
"Could we even call this a battle? Kido had thought as his sword slid carefully through a hobgoblin's neck, the cut so perfect that its head remained stuck until the body itself fell and it rolled onto the ground.
[You have killed a variant monster: black hobegoblin.]
[You have gained a Variant Essence Stone.]
[You have received an attribute: The Mad Swordsman.]
"Oh I received an attribute!!?" he exclaimed, stopping suddenly in his tracks, his eyes wide, he looked like he didn't believe it. Rare are those who receive attributes among varying, in a tribute of a hundred souls, only one, among the elites has a chance of acquiring them.
It is by acquiring an attribute that you receive a chance to become a mutant.
Attributes are passive abilities, they are at the same level as skills, it will depend on the rank but once an attribute is acquired, it will remain activated until the death of its bearer.