Ranking system
For humans:
Dormant: [this is mc's rank right now. Just a normal human in the process of becoming something more powerful].
Sleeper: (this is what the mc's rank would be after he finished the first trial, he's already half way there he just has to finish.)
Awakened
Ascended or the other name (master)
Saint or the other name (Transcendent)
Sovereign or its other name (supreme)
This is all up to the latest chapter in terms of human ranks.
Now for nightmare creatures:
Nightmare creatures have ranks and classes:
This is the ranks:
Dormant
Awakened
Fallen
Corrupted
Great
Cursed
Unholy
That's all for ranks, now for classes:
Beast - 1 soul core
Monster - 2 soul cores
Demon - 3 soul cores
Devil - 4 soul cores
Tyrant - 5 soul cores
Terror - 6 six soul cores
Titan - 7 soul cores
What the mc is fighting in these ch are awakened terror which should not be possible.
And the strongest rank is : unholy titan.
An unholy titan was mentioned once and it fought a deity so it's similar to a god.
And soul cores are cores that gives more energy to the beasts and most importantly…. Intelligence and abilities which is very scary.
Weekly Power Status
-- Power
Ranking 
-- Power
stone