Eikons

An Eikon is a being that is given life, form, and reason by fervent belief. While an ideal can be created this way it only becomes an Eikon if anthropomorphized. Given some form and identity, the most common form of an Eikon is that formed around a deviation in belief around a god’s teachings. In some, rare cases these Eikons can become living gods if they are accepted and assimilated by the god which they were based off. Thankfully, the process of summoning an Eikon is much harder than believing in one.
While looked down on, worship of an Eikon that isn’t manifested is not a crime, at least officially. Summoning one however is. Beings with god like power and a ravenous appetite for arcane energies and faith and motivated by the belief of its followers makes for a destructive combination.
Like many things in Belthuran Eikons are dependent on the Arcane, the purer the better. They are beings of the Arcane, constructs of faith made by a collective belief powerful enough to cause their formation. They are unable to sustain a physical form outside of the Arcane. Their followers will gather physical Arcane energy, often from Crystal Gardens or magical items. The most sought-after form of offering is from a sentient being that has undergone Crystallization fully. The mix of arcane energy and a soul makes for a potent fuel for an Eikon. The more such offerings the stronger the Eikon's body, as well as the hunger the Eikon has. An Eikon places a strain on the world as they draw in the arcane energies near them to help sate that ravenous hunger. Places of heavy arcane saturation lessen the need for offerings but can overtime drain the arcane energies present which can be dangerous in less saturated areas.
An Eikon's body once destroyed does nothing to harm the Eikon itself. So far the only known solution is destroying the faithful of the Eikon. It is a boon that very few sources of knowledge exist on how to summon an Eikon, the knowledge usually lost as often the summoner gives up their body and essence in the process. Any trying to fight a manifested Eikon is in for an intense fight against a foe that does not tire or suffer the wares of a mortal body.

Thralls

A sad fate awaits those present at the summoning of an Eikon as their souls are infused and corrupted by the manifesting Eikon claiming the soul for the Eikon. Overtime these thralls will find they worship the Eikon, the amount of time varies on each case. Overtime these thralls will find they worship the Eikon and desire to expand that belief. Those felled by an Eikon awaken under the belief they have always fervently believed in the Eikon as a fanatic. The exception being those whose souls are otherwise spoken for such as paladins, exceptionally devout clerics, warlocks, liches or for other reasons that prevent the soul being corrupted.

Eikon's Based on a god

If an Eikon is created based on an existing god that god can choose to absorb that Eikon into its portfolio and gain the power that Eikon had due to the faith. From there the god will use the Eikon to redirect the wayward followers to the gods' service. However, there is a reason that a god would not do so, especially were the Eikon summoned. Should a god find that an Eikon's personality and mission aid their cause they may choose to leave the Eikon be, let it run its course and absorb it or let it be forgotten. For example, an Eikon is created based on The Dawn King, or more specifically the Dawn King's hate of Undead, and both encourages and empowers its followers to fight the undead this Eikon is doing the Dawn King's will at no cost of power or faith from the god. In short, these Eikons can become agents of a sort, able to operate within the Material plane where the gods can no longer fully manifest. Should the Eikon be summoned then they are like avatars, again at no cost to the god.