[Not all points of the power system are explained here. Some details will be clarified to make the story clearer, while the rest will unfold as the events progress.]
The power system is based on something called Authority.
There are two ways to obtain Authority: either by inheriting it, or through System Pieces.
System Pieces are tools infused with Authority taken from the dead to prevent it from causing harm. By using them, even an ordinary human can wield Authority, though they come with various negative side effects. There are multiple types of Authority, each with its core abilities in addition to secondary abilities that differ from user to user, such as the Authority of Law, Fear, Madness, Fire, Lightning, and Miracles.
A wielder of Authority is called an Assimilator.
When assimilating Authority through a System Pieces, a person must perform a ritual to seal the immense power that the body cannot withstand, then gradually assimilate it.
Assimilators who inherit Authority do not need a sealing ritual, but they require a special ritual to activate the Authority, then gradually increase it in most cases. The speed of growth depends on talent.
When an Assimilator tries to use a System Pieces, it must contain Authority compatible with their own, otherwise the negative effects will be severe. For example, an Assimilator of Water Authority cannot use a fragment that contains Fire Authority, and vice versa.
To assimilate an Authority further, one must perform actions that resonate with its nature, such as:
Authority of Law: you must enforce the law.
Authority of Madness: you must act like a madman.
Authority shapes itself to fit its wielder. If the wielder is obsessed with justice, the Authority grants secondary abilities to fulfill that obsession. A cook would gain secondary abilities to aid him in his craft, just as an investigator, a fighter, or a magician would gain ones suited to them
The core abilities of each Authority are fixed and do not change, while secondary abilities differ from person to person.
There are two types of System Pieces:
1. Ancient Pieces
These fragments have existed naturally for thousands of years. Their negative effects are much lower, but they have become extremely rare in the present era, with only six ancient fragments remaining. When used to gain Authority, the success rate is high.
2. Artificial Pieces
These are divided into two kinds:
High quality: crafted by inscribing sets of runes which differ from fragment to fragment onto specially made tools. Authority is sealed into them after killing an Authority wielder and chanting the inscribed runes in an ancient language. Their negative effects exist.
Low quality or imitations: created by inscribing runes onto any chosen object, into which an Assimilator seals a portion of their power. These tools are much weaker than high-quality fragments. Their negative effects more dengrus than others types. they degrade quickly, with most working only once before losing all Authority or exploding in the user's face for being unable to contain it. They cannot be used to obtain Authority.
When an Assimilator dies and a System Pieces near them carries the same Authority or at least runes linked to their Authority, even without being infused the fragment absorbs that power.
If no System Pieces is present, in most cases the Authority spirals out of control and causes massive destruction before dissipating and merging into the air. At that moment, every wielder of the same Authority feels a surge in their own power.
However, if there are many wielders of that Authority, the surge becomes negligible, and sometimes the Assimilator does not notice it at all.