There are three main groups of supernatural enemies that a knight may encounter; the Undead, Demons, and the Fallen. All of them, while different, do share a similar trait; Darkness. This darkness makes them inherently the enemies of mortal-kind, from humans to insects, as they wish nothing but absolute rule over hell, the mortal plane, and heaven.
The undead are many and possess skills that makes even the stalwart demon-slayer hesitate in their presence. They all share similar traits, but there are noteworthy subgroups among the undead.
• Non-living: Healing does not work on undead, as the negative energies that keep them 'alive' reject the positive energies from healing.
• Critical Immunity: The undead lack the need of vital organs, keeping them around more or less to provide more cushion before being destroyed. Due to this, hitting them in vital areas such as the heart does not do anything additional and they often keep coming.
• Poison & Disease Immunity: Their organs have stopped working, making poisons and diseases obsolete.
• Infinite Stamina: Like the most scary thing among the undead besides critical immunity is their ability to keep an infinite supply of stamina. They do not sleep, eat, drink, or tire.
The Hoard is a group of undead that is commonplace among stories and games, from the zombie to the skeleton, they are all low-sentient but numerous creatures. Likely the only difference being is that zombies can range from sluggish to sprinters, depending on their injuries before death. They are brought back using negative energy that make up the layers of Hell.
Revenants are powerful types of the Hoard that have been possessed by Spirit Demons, either of zombie or skeleton corpses, but more commonly skeletons. They are normally seen with blades and some sort of armor, making them great melee opponents, but sometimes can get lucky and catch the Spirit Demon possessing a new corpse. Beware, however, even if you can catch one being newly possessed and without weapons - they are still physically powerful.
The second most feared undead is the dark magician that has been granted darkness from demons. Through ritual and a blood oath that binds their souls, these powerful skeletal magi are not to be underestimated. Thankfully, despite popular myths, not all Liches possess a phylactery. The ones that do are likely among the most powerful of their kind.
• Phylactery: Not much is known about these dark artifacts, but what is known is that they house the soul of the Lich in question, so if their body is destroyed, they may seek another one out until this 'Soul Jar' is destroyed.
Undoubtedly the King of the Undead. These rare individuals have done something so dark and twisted it cannot be called anything but an abomination. Vampires are the result of when a human or one of the Fallen have merged their souls with that of a demon. This results in a strange, but very powerful creature. Most traits that vampires have are symbolic, coming from their twisted soul's darkness, rather than scientific biology.
• Sun Weakness: Nullifies infinite stamina and all powers besides mist whenever it can see the sun. Since sun symbolizes life and the vampire is effectively dead, it weakens them.
• Blood-Drinker: An ironic symbolic relationship between the dead and the living that requires the vampire to feed on the living. Without it, they become weaker and if left unchecked, they become so weak as to mimic paralyzation. They cannot died from starvation from blood.
• Heart Weakness: If staked through the heart with wood, the vampire becomes paralyzed. However, the more powerful the vampire, the more the wood must be symbolic for the individual vampire. One example is say the individual merged their soul with a demon while in the bath with a rose in the room. The slayer would then have to dip the wood in water that has rose petals. The least reliable way of defeating a vampire.
• Enhanced Strength & Speed: Vampires gain a great amount of energy from the merge, resulting from strength that is able to bend solid steel blades and the ability to run as fast as a healthy horse.
Demons come in many forms and have plagued the mortal world for as long as anyone can remember, all the way back into the days of Ancarth the Fifth. These beings of darkness think of nothing else but to rule the mortal world and the heavenly realm and will stop at nothing to achieve their goals.
• Inhuman Strength & Endurance: The strength of any demon, no matter how harmless-looking they are, far outweighs that of any normal human. Their endurance is legendary, though their pools of stamina are not infinite.
• Darkness Affinity: All demons have an affinity to the darkness, granting them resistance to darkness-like powers and abilities and granting them complete vision in the darkness.
• Hardened Skin: Demon skin is renowned to be as strong as any steel made, which both serves as effective armor if one is willing to skin one after battle and an armor replacement for living demons.
Warrior demons are the generic-type demons most will run into. Though not any less dangerous than you'd expect, they are the least powerful of all the demons, making up for most of the cannon-fodder.
• Melee Experts: Experts in melee combat, ranging anything from polearms to longswords.
Second to last, these demons are coated in pitch black and sprint at extremely fast speeds, matching that of a healthy horse at full gallop. Besides their speed, their hands are made of black steel-like metal that seems to be in the shape of a crescent moon.
Demons that have all but become the shadows of any world, able to shape shift into flat-like shadows objects. While not extremely strong (as far as demons go), they are more akin to assassins, sliding behind their opponent and striking with deadly force. They often use dark magic or dagger-like blades.
An unusual type of demon that is more akin to a ghost than a demon. While on the mortal plane they can become completely invisible and are the only demons with the ability to possess dead bodies and sometimes weak-willed living humans and animals. In Hell, they looked like a transparent blue warrior demon. However, don't fool yourself that they are weak, for they're at least as twice as strong as warriors, faster, and hold deadly spirit-poison blades.
Succubus / Incubus
The third most powerful type of demon, not because of their unusual strength for their size, or agility, but rather their natural and supernatural ability to seduce. Both the female and male versions use beauty of their natural forms that, while being demon-based, does look extremely attractive. They also employ supernatural abilities of seduction to conjure illusions in a dream-like state that mimics your deepest want and offers it to you. In this state, the demon is slowly absorbing your soul until you're nothing but an empty body.
Second most powerful and certainly the most visually frightening of all the demons. These demons are giants among demons and colossus beasts among men. Most of their power comes from the obvious strength and endurance of their size, often requiring at least a legion of knights to defeat.
The generals of Satan and even Satan can be considered one of the Awakened. These demons are beasts of pure darkness and power, ranging from full magi to melee fighters that can match a legion of Praetor Knights. It is hard to describe the Awakened, when each one is individual and with individual strengths. There's believed to be thirteen in total, including Satan.
The Fallen are those who were, once, warriors and saviors of heaven. They have since been corrupted by darkness and even though they are under the snare of Satan, still have ambitions to create their own immortal kingdom and destroy Hell and Heaven in the process.
• Darkness & Light Familiarity: These unique individuals, having come from holy heights to dark depths are familiar with both the light and the dark, making them not wholly immune, but resistant to both types.
• Corrupt: With a strange mix of divine origin and dark taint, these individual sustain themselves with nearly infinite pools of stamina, endurance, and strength.
The original fallen knights from when Ancarth the Fifth followed the Archangels into Hell. Though corrupted and tainted, these knights still hold onto gifts that were given to them by the gods, though they are powered by their own darkness and souls rather than divine might. The Darkriders are the elite of the forces of darkness, and are by far one of the hardest to defeat.
The original ten Archangels that sought to destroy all and create their own kingdom. These tainted heavenly beings are as powerful as they are beautiful. Though no one is sure what they are capable of, if anything anymore.