Fantasy

In the darkest and most cruelest dungeon is the birth of a specie who lives his every day life trying not to fall prey to the claws of the predators.
    To survive amongst predators, one most shed off the flesh of a prey and take on the skin of an even bigger predator.
    Power Ranking
    Note
    The numbers refer to existential value, and all lifeforms has it.
    ADVENTURER GUILD POWER RANKING
    Lv 1 - 20 = F (1 - 49)
    Lv 20 - 30 = E (50 - 99)
    Lv 30 - 50 = D (100 - 499)
    Lv 50 - 60 = C (500 - 999)
    Lv 60 - 80 = B (1,000 - 4,999)
    Lv 80 - 100 = A (5,000 - 9,999)
    Lv 100 - 200 = S (10,000 - 19,999)
    Lv 200 - 500 = SS (20,000 - 29,999)
    LV 500 - 900 = SSS (30,000 - 49,999)
    LV 900 - 1000 = XS (50,000 - 99,999)
    SPIRITUAL ENTITY RANKING SYSTEM BELOW
    ■MONSTERS AND OTHER NON-HUMAN LIFEFORMS
    ●Apocalypse > 100,000,000 - 1,000,000,000
    ●Armageddon > 10,000,000 - 99,999,999
    ●Cataclysm > 1,000,000 - 9,999,999
    ●Disaster > 100,000 - 999,999
    ■HUMAN
    ●Transcendent > 100,000,000 - 1,000,000,000
    ●Warlord > 10,000,000 - 99,999,999
    ●Mystical > 1,000,000 - 9,999,999
    ●Heroic > 100,000 - 999,999