Horo's Eye trait was so simple originally that even the members and headmaster of silence understood that. They were so black that the only reason you could notice his pupils was an extremely thin white line separating his iris. All they could do was drawn your consciousness into an inner realm of darkness and he had to have a stronger mind for that to even work, But after the constant development, evolutions before entering the evolved realm, and then entering the evolved realm, they were something on a totally different level.
After merging the Coffin Chains relic, the ability Chains of the Damned were born. The chains were extremely durable and could make contact with physical and ethereal entities or things. They could seal energy and targets and drain life force and souls. They allowed Horo to pull physical entities into the inner realm of his eyes.
When he merged the dimensional pearl it allowed the ethereal inner realm to become a true dimension of its own and he could store objects and even living beings there. The space grows the stronger he becomes.
His Soul subjugation spell linked to his eyes due to his auxiliary spell "Link" and Even merged with his eyes and evolved them slightly. He could pull in the souls of entities and try to subjugate them or hold them imprisoned there until their will breaks as it is so dark it gives an effect that minutes are years.
Lastly he created and merged the "Kurai mono tachi" with his trait which caused the last evolution before his advancement. They caused his inner realm to become the realm of the dark ones, and they helped in subjugating souls and marking them for control or devouring them to reinforce the realm and strengthen themselves.
When it comes to his abilities as a spell caster he has a special situation. His Soul Idol is an exact replica of what should be a relic, but seemed like something beyond a relic now, on his back, the black tree. Furthermore even without the use of his auxiliary spell "Link" they formed a connection that seemed to exceed the bounds of a world, as if the idol was a shadow of the Tree. His soul module was special and was not just within his brain, but directly connected to his soul, as his mother used some special methods to make this possible; this was why his module could display everything related to him yet it still couldn't categorize what the tree was, but his mother called what it originally was when he was a fetus "The Seed of Misfortune".
The connection between the two created a special situation that he had yet to see all the benefits of, but two of them was that it made some of his spells directly compatible with his trait's ability or made them passive and able to active on their own like the Link spell.
Horo wasn't the most talented spell caster as he didn't have nearly as many spells as other casters nor did he have a specific affinity, but the quality and uniqueness of his spells was definitely among the top tier of spell casters, maybe even among the greatest on earth yet no one knew.
He had his core spell Transmutation, and six auxiliary spells.
Transmutation was perfect for his pure and robust negative energy as it could make it extremely durable physical object and weapons. It would also be of great use in specific trades he may want to pursue.
The link spell was extremely special and was created by his mother after researching large amounts of relics, treasures and other spells. It became passive due to the connected formed between his soul idol and Tree "Relic".
Now it was able to automatically activate and link anything related to his being such as treasures, spells abilities techniques and etc. that were compatible raise their resonance to a higher level to either merge, change their paths of evolution, or have better synergy.
Energy armor was a very simple spell that a large amount of spell casters used due to their bodies not being as reinforced as trait masters, However with his mother being aware of the phenomena of his fetus absorbing ridiculous amounts of negative energy while also condensing and purifying it she knew that could make this spell more special and geared for him specifically. She modified and enhanced so that it would be more durable and efficient based off of the quality of the energy being used to supply the spell matrix, as well as have recovery abilities, adjustment features, enhanced external armors, efficiency and energy preservation features. This spell was linked with black light and allowed black light to have a second gear.
Illusory grip was sort of a telekinetic ability that allowed the user to control anything surrounding a target such as air particles or energy and influence them by pushing, gripping, lifting or whatever intended.
Grant life was developed by Katina after studying the soul, consciousness, awareness and the ability to name spirits.
Decomposition was originally an arrangement of enchantments and inscriptions made with rare materials to form an extremely large matrix used to decompose any matter into nothing. It needs extremely pure negative energy that is condensed through a purifying filtration system, and it is used world wide rid the world of waste. It originally couldn't be embedded on an Idol and be used by spell casters since first of all no one had energy that pure or abundant except progenitors, secondly no ones was able to forge the matrix within their soul dimension nor apply it to their idol. Katina made it so that Horo's soul module could help him with the process, as she knew his energy may just be pure enough to use the matrix. The draw back was that he could only use it with his physical body while the rate of decomposition would be very slow if contact is constant and extremely slower if not. Luckily a a link was formed with his transmutation spell and gave this spell an extreme boost.
With everything that he learned from silence and all of his abilities by the age of 18 and being an adult at the peak of the evolved realm, his strength was unimaginable, but he always held back so no one knew his true power, he wanted it this way because he had plans to not be in silence forever. The resentment that slowly built up over the years, but never showed, was like a raging volcano ready to erupt.