Could Contain Spoilers! Read With Own Discretion!
Monster Categorization
Monsters have 7 Classes and every Class has 3 Tiers
Class 1 Tainted
Class 2 Rotten
Class 3 Corrupted
Class 4 Horror
Class 5 Abomination
Class 6 Calamity
Class 7 Apocalypse
Classification: Class of the X Tier, for example: Horror of the 3rd Tier
Human Categorization
Evolved is the name of the human group that can evolve and also the first ranks name. It will get confusing at times.
Rank 1 Evolved
Rank 2 Ascended
Rank 3 Transcended
Rank 4 Stellar
Rank 5 Ethereal
Rank 6 Celestial
Rank 7 Empyrean
Humans have 7 ranks. They become Evolved with their first kill which unlocks their first transformation. They can then collect 1000 Life Essence and hunt a monster to rank up and become Ascended.
Life Essence Counting
The way to count the amount of absorbed Essence is with this formula: Monster's Class^ Monster's Tier, for example a Horror of the 3rd Tier is a 4th Class monster, which means it contains 4^3= 4*4*4=64 Life Essence. Monsters of the 1st Class give the amount equal to their Tier: Tainted of the 3rd Tier gives 3 Life Essence.
Abilities, Transformations, Passives
When becoming an Evolved, everyone receives one ability and one transformation, both of them related to the monster they killed. There is also a chance to receive passives, which are always active. There are two kinds passives for ability and for transformation, one is always active and one is active when transformed.
Abilities and transformations cost Essence to maintain, passives don't.
Items
Monster can give Items, which can be summoned anytime. They range from weapons, armor, clothing... etc. If summoned they cost Essence to maintain.