My own fantasy, pagan setting happening around 400-300 BC, located somewhere what would be today’s Europe. The times of Iron Age, continental Celtic history, but with mythical beasts and gods actually existing at the fringes of civilization.

Magic also plays a much more potent role in the world. Although it is extremely hard to master, people have learned to employ some of the essence into everyday life. For instance, “magic” is used during rituals, while praying and interacting with the gods, and as very minor protective spells. An essence can be embedded into a bronze torc in order to protect its wearer by granting them safer passage through the wilderness or greater resilience in battle. Magic is very closely connected with the surrounding nature and people’s bonds with the land and its beings.

An undead hybrid creature magically sewn together by an elder healer. Someone you’d call a “druid” in today’s closest popular terms: a person who taught generations, who helped in spiritual guidance, and could heal with various remedies as well. In this setting, a wielder of essence and someone who loved to play with the boundaries of nature’s capabilities. The function of his creation was solely to protect the tribe grounds and its people. The creature could not eat, it could not breed, nor have a mind of its own. It could only be commanded by its creator, or by a person the druid has chosen to share this power temporarily. The hybrid’s life was supported only by “necromantic” magic, an anti-energy existing alongside the natural essense of living beings.

Due to an unforeseen incident, the creature became permanently bonded with a human soul and achieved consciousness, developing a distinct personality of man and beast(s).
After the bonding, the creature became mortal (with a long lifespan, but still, very much mortal). He far outlived his people and was later left to roam the land, becoming the source of many local legends. He was feared by some, and worshipped by others. Previously reffered to as “the guardian”, or simply “the monster”, he was eventually granted with a new name by other tribes – Arcusios.

Arcusios has features of a few creatures: the height and general posture of a horse, strong hind legs that let him stand upright, long-fingered front paws almost able to grab, and a mostly bare, white skull of a horse with long canines. The skull can be bare or covered with scar tissue. His body can be covered in scars where previous animals had them (or where the sections were connected), but it’s not entirely necessary to the design. There are various feathers attached to his mane – originally given by his tribe, later replaced with new, painted ones by the people who worshipped him. He can also appear with other decorations and paintings on his body, like bronze or coral jewellery, paint and colorful clothing.

The creation of Arcucios was preceded by a number of failed experiments. The village folk never admitted to them, because necromantic magic was feared among other tribes. These initial, failed creations died either instantly, or only after a short period of time. The elder was far too fascinated with the limits of the essence to give up, as he’d wished to teach his people to follow in his steps as he tried to create something perfect for them to protect them long after he was gone. Arcusios became the first and only (as it is commonly believed) “working” hybrid that served its purpose. When not in battle with other tribes, it was put to sleep in order to await the next calling.

During one battle, the village was taken by surprise and was wiped out, even with the help of the immortal beast fighting alongside them. When all seemed lost, Arcusios was tasked to save his creator, but in the moment of the man’s death, the essence he’d gathered over the years and his very soul had seeped into the creature. It was a last resort move to survive, but the man didn’t know what he’d wished for. He became bound to undeath, as long as his creation was still standing.

Their consciousness and personality melded into one. A chaotic howl of various wild things mixed together with a human mind. For a long time after the incident, Arcusios kept wandering the wilds, feeling lost and broken, trapped in the body of a terrifying creature, having lost everything they had, trying to understand how to exist. What was left of their humanity was limited to a scrambled mind, with the animalistic side of them constantly trying to have the upper hand.
This did not stop him from trying to live. Years of wandering had allowed him to watch everything from the safety of the woods or the veil of the night. He saw people, he followed their step and listened from afar, clinging to this shadow of his past life, trying not to forget how he used to be human. He also traveled with wolf packs, brought food to wounded animals and warned them of incoming threats, ensuring safe passage for both men and animal, somehow finding himself in both. To those who’d seen him, who’d ventured into the thicket to meet him, soon called him a guardian, or a monster god of some sort. 

Throughout his remaining life he met with a number of smaller communities, growing bolder with time. He tried to communicate his story to those who chose to listen, or rather, chose to see and use the essence to understand him. Most communities who gave him a chance saw the power of gods within him and provided closure. He settled in the wilds close to one of the tribes where magic was the most potent, and made it his lair. Arcusios once again became the protector, the reverent being. He lived through multiple wars and saw many generations rise and fall, feeding off of that energy.

During times of peace, he was dormant in his lair, visited by and cared for by his people until his power was needed again. However, the magic within those wilds changed him year by year, slowly turning him into an immortal, lich-like creature, that would forever sleep and become the new source of energy for others to thrive off of. Soon the people around him came and went without him realizing the passage of time, until someone sealed them away, deeming their essence too powerful and dangerous for the outside world. The knowledge of his lair became lost to time, and only the legends remained in local folk tales and songs of a terrifying creature dressed in gold and bronze and coral, ready to wake up when the world needed them once more.