Fighter Subclass based on the skill Rune Mastery of the class Rune Knight in the game Ragnarok Online.

Yet to make the lore, still balancing the gameplay.

Apprentice

Starting at level 3, you learn to forge magical runes and equip them on any type of weapons and equipment. During a long or short rest, you can forge up to 2 runes (1 offensive and 1 defensive) on the equipment. Each type of rune can only be activated once per turn and not simultaneously with other runes, a number of times equal to the Constitution modifier for each rune individually if it has an effect that requires its use. Multiple different runes can be placed on the same piece of equipment.

If a rune hasn't been fully used, it will stop functioning during the next long rest. If a rune caused a status effect, subsequent runes cannot trigger their own until the next turn.

During each long rest, you can forge a rune (offensive or defensive) onto an ally's equipment, up to a number of allies equal to your Strength or Dexterity modifier. The effects and number of uses are the same as if the rune forger used them, including the penalty for affecting an enemy already suffering from an altered state due to a rune.

At level 3, you gain access to and can forge the following offensive runes:

• Fire Rune: When placed on a weapon, you can activate it to ignite the area where the rune is placed without damaging the weapon. It can set flammable objects on fire upon contact and emits bright light for 10 feet and dim light for an additional 10 feet. When making a melee weapon attack during your action, you can activate this rune, which adds 1d8 fire damage to the attack. If the target fails a Dexterity saving throw, it takes 1d4 additional fire damage at the start of its next turn.

• Frost Rune: When placed on a weapon, you can activate it, causing the weapon to freeze without damaging it for 1 minute. If the weapon comes into contact with water or similar fluids, they freeze in a 5-foot area. When making a melee weapon attack during your action, this rune adds 1d8 cold damage to the attack. If the target fails a Constitution saving throw, its speed is reduced by 5 feet until the end of its next turn.

• Thunder Rune: When placed on a weapon, you can activate it and leave a copy of this rune on non-magical objects or surfaces. If used in this way, a thunderous sound will echo from the location of the rune within a chosen time frame of up to 1 minute. When making a melee weapon attack during your action with this rune, it adds 1d8 thunder damage to the attack. If the target fails a Strength saving throw, it is pushed 5 feet away from you.

You also gain access to and can forge the following defensive runes:

• Protection Rune: While this rune is equipped on armor or a shield, you gain a +1 bonus to AC. This is a permanent effect and does not consume charges. It cannot be used together with the Elemental Resistance Rune.

• Elemental Resistance Rune: While this rune is equipped on armor or a shield, you gain resistance to fire, cold, or thunder damage (chosen when forging the rune). This is a permanent effect and does not consume charges. It cannot be used together with the Protection Rune.

• Safeguard Rune: While this rune is equipped on armor or a shield, you can use your reaction to gain advantage on a saving throw involving Dexterity, Constitution, or Strength.

• Agility Rune: While this rune is equipped on boots, you can use your bonus action to gain an extra 10 feet of movement for 1 minute. If another rune is used during this time, the effect ends early.

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Rune Veteran

Starting at level 7, your mastery of runes deepens. You can now forge up to 4 runes (2 offensive and 2 defensive). You can also forge enhanced versions of the runes you already know and gain access to new offensive runes:

• Enhanced Fire Rune: The damage of the Fire Rune increases to 2d8 fire damage. If the target fails its Dexterity saving throw, the additional fire damage at the start of its next turn is 1d6.

• Enhanced Frost Rune: The damage of the Frost Rune increases to 2d8 cold damage. If the target fails its Constitution saving throw, its speed is reduced by 10 feet until the end of its next turn.

• Enhanced Thunder Rune: The damage of the Thunder Rune increases to 2d8 thunder damage. If the target fails its Strength saving throw, it is pushed 10 feet away.

• Poison Rune: When placed on a weapon, this rune coats the blade in poison. During a melee weapon attack, it adds 1d8 poison damage. If the target fails its Constitution saving throw, it is poisoned until the end of your next turn.

You can also forge enhanced versions of your basic defensive runes or new defensive runes:

• Enhanced Protection Rune: The Protection Rune now grants a +2 bonus to AC. This effect is permanent and does not consume any charges.

• Enhanced Elemental Resistance Rune: While equipped on armor or a shield, you gain resistance to two types of elemental damage between fire, cold, or thunder (chosen when forging the rune). Only one type of resistance can be active at a time, and an additional action is required to switch between them. This switch consumes charges. It cannot be used together with the Protection Rune.

• Mountain Rune: While equipped on boots, you can use your bonus action to gain 10 feet of climbing speed, 10 feet of long jump distance, and 3 feet of vertical jump height for 1 minute. If another rune is used during this time, the effect ends early.

• Guardian Rune: While equipped on armor or a shield, you can use your reaction to reduce the damage of an incoming attack by 1d8 + your Constitution modifier.

• Fortitude Rune: While equipped, you can activate it to gain a +1 bonus to any type of saving throw.

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Superior Runes

At level 10, you achieve a new level of mastery in rune forging. You can now forge up to 6 runes (3 offensive and 3 defensive). You can also forge a second rune for your allies, as granted by the level 3 ability, but it must be a different type (one offensive and one defensive).

Through your rune training, you gain the ability to forge the following offensive runes:

• Blood Rune: When making a melee weapon attack during your action, this rune adds 1d8 necrotic damage to the attack. You heal a number of hit points equal to the necrotic damage dealt by this rune.

• Lightning Rune: When making a melee weapon attack during your action, this rune adds 2d8 lightning damage. If the target fails a Dexterity saving throw, it suffers disadvantage on its next attack.

• Destruction Rune: When making a melee weapon attack during your action, this rune adds 2d8 force damage. This attack ignores non-magical damage resistances. If the target fails a Strength saving throw, it is knocked prone.

You also gain access to the following defensive runes:

• Arcane Protection Rune: While equipped on armor or a shield, you can activate this rune to gain advantage on a saving throw against spells or other magical effects caused by spells.

• Absorption Rune: You choose a damage type between Fire, Cold, Thunder, Necrotic, or Radiant. While this rune is equipped on armor or a shield, you can activate it when taking damage of the chosen type to absorb damage equal to your Strength modifier + Fighter level, healing the same amount instead of taking damage. This rune can only be used once and can be forged once per long rest for each selected ally or the forger.

• Revitalization Rune: While equipped on armor, shield, or weapon, you can use your bonus action to heal yourself for 1d8 + your Constitution modifier. However, this rune needs a brief cooldown, so it cannot be used in two consecutive turns.

Rune Potential

At level 15, you attain absolute mastery over rune magic. You can now forge up to 8 runes (4 offensive and 4 defensive) for yourself. You can grant selected allies, as allowed by the level 3 ability, 2 offensive and 2 defensive runes.

You gain the ability to activate two runes simultaneously once per turn. Both consume their use as normal, and both require saving throws if applicable. However, if both saving throws fail, only one effect occurs, and the second is canceled. The player can decide which rune effect takes place.

Runic Overcharge

At level 18, once per long rest, you can roll a d8. All of your runes and 2 runes of allies within 30 feet of you gain additional activation charges equal to half the value rolled (rounded up).