Here's some lore!

Devourers are classified and ranked by 'type', 'rank', and 'class'.

A type of devourer is decided by what ability based on the Concept of Devouring they have.

A Devourer with a Skill-Glutton type can eat the skills and expertise of the ones they devour them from in combat.

A Devourer with a Material-Glutton Type can eat through any material by creating a vacuum of energy that sucks in the objects and destroys them while gaining a pool of adaptive power that is processed into strength and durability.

There are many different types, but all gain in power and versatility upon ranking up.

Levy-Class Devourers are little more than vicious animals in strength and usually come in the form of blood-colored animals that give off an extremely off-putting aura. They can be handled by a group of normal people if ganged up on.

The Levy-Class is broken into five levels.

Peasant,

Recruit,

Trained,

Apprentice,

Pre-soldier.

Then they can evolve into the Soldier-class which are much stronger, but can still be handled by people without supernatural abilities. Ranks match military ranks and there are four of them.

Private,

Corporal,

Sergeant,

Command Sergeant,

Additionally we reach the beginning of the ranks in which people without magic or Ki have no chance to beat them at all.

The officer class.

Second Lieutenant,

First Lieutenant,

Captain,

Major,

Lieutenant Colonel,

Then we reach the levels of the 'True officer class' in which they have the power to level villages and outskirt towns. They have three levels.

Colonel,

Brigadier General,

Major General,

Lieutenant General.

Upon the next evolution we have the 'Absolute class' The ones who are usually hibernating and only awaken when the Prime Devourer is nearing the world or preparing to be summoned.

Waking one can end with such disaster that cities will shatter and the world will shake.

General,

First Powered General,

Second Powered General,

Grand General,

Finality General.

General of the Prime.

Finally, we see the final enemy of humanity, the Prime Devourer.

It is said to be able to eat the world.