Demonic Magic / The Demon King Magic

Magic

Primary Magic: Demonic Magic / The Demon King Magic
Caster or Holder: Caster / Lost Magic
Description: Demonic Magic or The Demon King Magic is a form of Darkness Magic that can only be used by Demons. The origin of this magic is unknown but believe to be created and used by the previous Demon King. Mortals who have attempted to use this kind of magic have perished and in saying that, Demon Slayers have been known to be able to absorb this magic and live.

Taehyung himself cannot use this magic, in fact he has no form of magic he can use what so ever. Instead, it is Adramelech who uses this magic and must take control of Taehyung's body in order to use it. Conjuring dark magicks, Lech bends the darkness to his will, creating various attacks, objects and shields out of pure Demonic Energy. This energy is black and red, the two contrasting power that is believed to have once been the power of the Demon King.

Strengths:

• Recieves half damage from all forms of Darkness Element/Magic/Spells.
  
• This form of Darkness Magic can only be used by Demons and can ONLY be absorbed by Demon Slayers.
  
• This Magic molds to the user's capabilities, taking the form of anything the caster can think of, making it a useful and a well adaptable form of Darkness Magic.

Weaknesses:

• Weak against Holy/Light Element/Magic/Spells.
  
• Can be absorbed by Demon Slayers.
  
• Its versatility means that it will be rare for the user to be able to dominate in one field, and must use all aspects of there magic in order to properly fight.
  
• Only Adramelech can use this magic and that is only possible when he takes over Taehyung's body, Tae cannot use this magic or any magic in fact and must rely on the demon in order to defend himself.

Lineage:
Archmage's Seal:
Description: There was once a great and powerful mage named Merlin. He was a master of the elements and knew a variety of spells. It was said that this was because he was given a gift by the goddess Hecate, a magical symbol on his shoulder. Those who bear the same lineage as Merlin posses the mark on their left shoulder.
Ability: Temporarily allows the user to change the element of his/her magic into:  Fire, Water, Earth or Air.
Usage: This ability has a 4 post duration and 5 post cooldown and works as long as the duration is up on any spells cast. If a duration spell is affected by this ability it will stay that element until this ability goes on cooldown after use. The new element is either added to the spells with no element or changes the element completely to the element granted through this ability.

Unique Abilities:
Rune of Abaddon (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Abaddon. This rune permanently increases their max Mana by 10% and is removed when they revert back to Taehyung. This percentage is raised by 5% for each rank they level up.

Rune of Azazel (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Azazel. This rune permanently increases their max movement speed and spell damage by 15% and is removed when they revert back to Taehyung. This percentage is raised by 5% for each rank they level up.

Rune of Beezlebub (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Beezlebub. This rune permanently increases their max resistance and physical strength by 15% and is removed when they revert back to Taehyung. This percentage is raised by 5% for each rank they level up.

Spells:
Name: Demonic Lightning
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 2 Posts
Description: Adramelech clenches one hand and thrusts it forward, instantly releasing a single target bolt of black and red lightning. Although it looks like lightning and acts very much like electricity, the spell itself is actually of the Darkness element. The bolt can reach up to 60 meters away, travels at 45 meters per second and can cause piercing damage.
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.

Weaknesses:

• Can only target a single enemy instead of multiple targets.
  
• Adramelech must have control over Taehyung's body in order for this spell to be used.

Name: Demon Impact
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 2 Posts
Description: Adramelech throws a black and red ball of Demonic Energy that is roughly three inches in diameter. The spell can reach up to 60 meters and travels at a speed of 45 meters per second. When the ball connects with an object or surface, it explodes with an area of effect of 30 meters. Anything in the 30 meters is drawn in to the center of the attack instantly to receive the full damage from the Darkness Element and causes damage over time. The initial damage is 20hp and does an additional 5hp per post for the next four posts.
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.

Weaknesses:

• This spell does 50% less damage due to being an AOE.
  
• The damage over time has no effect against those who use Holy/Light Element magic.

Name: Contract of the Demon King
Rank: D
Type: Offensive Darkness
Duration: 3 posts
Cooldown: 4 posts
Description: Adramelech causes multiple arms created from red and black Demonic Energy to rise up out of the ground and bind his enemies in an area of 30 meters. The spell can be cast 60 meters away and the speed at which the arms move is 45 meters per second. When they have taken hold on an enemy, the arms deal Darkness element damage and these arms are destroyed when the spell ends or when they are hit by two D-Rank spells or one C-Rank spell or one D-Rank Holy/Light Element spell.
Strengths:

• Binds enemies for a period of time to make them an easier target or for an opportunity to escape.

Weaknesses:

• This spell does 50% less damage due to being an AOE.
  
• Each arm only requires one D-Rank Holy/Light Elemental spell to destroy it.

Name: Malevolent Strike
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 2 Posts
Description: Adramelech raises an arm forward with an open hand, this hand is engulfed in an orb and black and red Demonic Energy that fires multiple homing blasts of Darkness Element. These blasts act like streams, traveling 45 meters per second and up to 60 meters away and can cause piercing damage.
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.

Weaknesses:

• Deals 75% less damage than other spells due to targeting multiple targets and can only deal full damage if ALL hit a single target.
  
• During particularly bright, sunny days, this spells ranger only reaches 50 meters away rather than 60 meters due to effects of light.

Magic

Primary Magic: Demonic Magic / The Demon King Magic
Caster or Holder: Caster / Lost Magic
Description: Demonic Magic or The Demon King Magic is a form of Darkness Magic that can only be used by Demons. The origin of this magic is unknown but believe to be created and used by the previous Demon King. Mortals who have attempted to use this kind of magic have perished and in saying that, Demon Slayers have been known to be able to absorb this magic and live.

Taehyung himself cannot use this magic, in fact he has no form of magic he can use what so ever. Instead, it is Adramelech who uses this magic. Conjuring dark magicks, Lech bends the darkness to his will, creating various attacks, objects and shields out of pure Demonic Energy. This energy is black and red, the two contrasting power that is believed to have once been the power of the Demon King.

Strengths:

• Recieves half damage from all forms of Darkness Element/Magic/Spells.
  
• This form of Darkness Magic can only be used by Demons and can ONLY be absorbed by Demon Slayers.
  
• This Magic molds to the user's capabilities, taking the form of anything the caster can think of, making it a useful and a well adaptable form of Darkness Magic.
  

Weaknesses:

• Weak against Holy Element/Magic/Spells.
  
• Can be absorbed by Demon Slayers.
  
• Its versatility means that it will be rare for the user to be able to dominate in one field, and must use all aspects of there magic in order to properly fight.
  
• Only Adramelech can use this magic, Taehyung cannot and is unable to defend himself without the aid of the demon inside him. (I saw this in your description as well, I assume Adramelecht is a demonic entity that takes control of Taehyung in order to cast his magic. If so, make sure to point that out as well. You already have it in your spells, but since this is a vital part of your magic it is better to put it up in your description as well. And since I feel this is more plot then an actual ability you can't have it listed as a weakness in every spell, think of weakness like you have in your description, which spells are easy for Demon Slayers to eat etc,)
  

Lineage:
Archmage's Seal:
Description: There was once a great and powerful mage named Merlin. He was a master of the elements and knew a variety of spells. It was said that this was because he was given a gift by the goddess Hecate, a magical symbol on his shoulder. Those who bear the same lineage as Merlin posses the mark on their left shoulder.
Ability: Temporarily allows the user to change the element of his/her magic into:  Fire, Water, Earth or Air.
Usage: This ability has a 4 post duration and 5 post cooldown and works as long as the duration is up on any spells cast. If a duration spell is affected by this ability it will stay that element until this ability goes on cooldown after use. The new element is either added to the spells with no element or changes the element completely to the element granted through this ability.

Unique Abilities:
Rune of Abaddon (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Abaddon. This rune permanently increases their max Mana by 25% and is removed when they revert back to Taehyung. (Make this 10%, With the 5% increase for each rank you level up)

Rune of Azazel (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Azazel. This rune permanently increases their max movement speed and spell damage by 15% and is removed when they revert back to Taehyung. This percentage is raised by 5% for each rank they level up.

Rune of Beezlebub (Passive) - When Adramelech takes over Taehyung's body, runes form all over his skin which constantly move. One of these runes is the Rune of Beezlebub. This rune permanently increases their max resistance and physical strength by 15% and is removed when they revert back to Taehyung. This percentage is raised by 5% for each rank they level up.

Spells:
Name: Demonic Lightning
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 1 Post (At least 2 posts)
Description: Adramelech clenches one hand and thrusts it forward, instantly releasing a single target bolt of black and red lightning. Although it looks like lightning and acts very much like electricity, the spell itself is actually of the Darkness element. The bolt can reach up to 60 meters away, travels at 45 meters per second.
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.
  

Weaknesses:

• Can only target a single enemy instead of multiple targets.
  
• Adramelech must have control over Taehyung's body in order for this spell to be used.
  

Name: Demon Impact
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 2 Posts
Description: Adramelech throws a black and red ball of Demonic Energy that is roughly three inches in diameter. The spell can reach up to 60 meters and travels at a speed of 45 meters per second. When the ball connects with an object or surface, it explodes with an area of effect of 30 meters. Anything in this area is drawn in to the center of the attack instantly to receive the full damage from the Darkness Element. (Clarify the full damage from the Darkness Element. Is there an extra condition? I would consider putting in an extra effect since the spell deals 50% less damage)
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.
  

Weaknesses:

• This spell does 50% less damage due to being an AOE.
  
• Adramelech must have control over Taehyung's body in order for this spell to be used.
  

Name: Contract of the Demon King
Rank: D
Type: Offensive Darkness
Duration: 3 posts
Cooldown: 2 posts(Cooldowns always have to be one post longer than the duration)
Description: Adramelech causes multiple arms created from red and black Demonic Energy to rise up out of the ground and bind his enemies in an area of 30 meters. The spell can be cast 60 meters away and the speed at which the arms move is 45 meters per second. When they have taken hold on an enemy, the arms deal Darkness element damage and these arms are destroyed when the spell ends or when the arms receives sufficient damage. (Keep in mind the strength of others with binding spells, like you can easily bind D and C rank enemies for the entire duration. But stronger enemies may have an easier way of escaping and breaking free from your binding spell. Also consider that opponents even D rank should be able to break free from your binding spell. Like if they attack the hands with a couple of D rank attacks can they escape? How does light magic affect your darkness element.)
Strengths:

• Binds enemies for a period of time to make them an easier target or an opportunity to escape.
  

Weaknesses:

• This spell does 50% less damage due to being an AOE.
  
• Adramelech must have control over Taehyung's body in order for this spell to be used. (This can't be a weakness to every spell, since Adramelech is a plot which you can summon for every battle without any negative or positive side effects. It isn't a spell/ability/lineage. So you really have to think up of different weaknesses for your spells. Like you are using demonic abilities which are a form of darkness magic. Than consider for this spell the opposite element: Light and Holy users can break free more easily from these bindings)
  

Name: Malevolent Strike
Rank: D
Type: Offensive Darkness
Duration: Instant
Cooldown: 2 Posts
Description: Adramelech raises an arm forward with an open hand, this hand is engulfed in an orb and black and red Demonic Energy that fires multiple homing blasts of Darkness Element. These blasts act like streams, travelling 45 meters per second and up to 60 meters away.
Strengths:

• The spell is instant, requiring no charge and can be used on the fly with a long reach and fast movement. A resourceful spell that can be often used.
  

Weaknesses:

• Deals 75% less damage than other spells due to targeting multiple targets. (But what if they hit a single opponent than he/she will suffer full damage right)
  
• Adramelech must have control over Taehyung's body in order for this spell to be used.
  

I think I have made the necessary changes, or at least I hope so.