Mutantborn

Whether it is through expirmentation during their infant years or through discovering the ability to shapeshift, a Mutantborn is a fighter that manifests mutations to improve their martial prowess. These mutations can range from the claws of a werewolf to the breath of a dragon to many other physical features from well-known monsters. Some Mutantborns may be able to hide these physical mutations while other are not so fortunate.

Mutations

When you choose this martial achetype at 3rd level, you will gain several features called mutations, and will gain new mutations at 7th, 10th, 15th, and 18th level, as part of your anatomy adapting for battle. When you gain a level in this class, you can choose one of the mutations you picked at a certain level and replace it with another mutation from the same list used at that level.

Some of your mutations require your target to make a saving throw to resist the mutation's effects. The saving throw DC is calculated as follows:

Mutation save DC = 8 + your proficiency bonus + your Constitution modifier

Mutated Limbs

Starting at 3rd level, your arms and legs have taken a new form, improving your fighting capabilities and mobility. Choose two options from the Mutated Limbs list. You gain the benefits of those mutations, and can choose another option from the Mutated Limbs list when you reach 10th level and again at 18th level.

Aquatic Adaptation

With your webbed fingers and toes, as well as having scales around your limbs, you have a swimming speed equal to your walking speed and have advantage on ability checks against being grappled.

Bugbear's Arms

When you make a melee attack, your reach for it is 5 feet greater than normal.

Extendable Weapons

You can retract any simple or martial weapon with the light property into each of your forearms. You can extend them out of your forearms as a free action and they cannot be disarmed from you. You can only store one weapon into each arm at a time, and must finish a short rest to replace one weapon extended from your arm with a different one that also has the light property.

Otherwordly Wings

You can grow angelic or fiendish wings using a bonus action. Once you do so, you have a flying speed equal to your walking speed for the next 10 minutes, and must finish a short or long rest to be able to use your wings again.

Satyr's Legs

Your legs are transformed into a beastly form, giving improved mobility. You add 10 feet to your movement speed, and you double your jumping distance.

Spiderclimbing Feet

You have a climbing speed equal to your walking speed. In addition, you can move up, down, and across vertical surfaces and upside down along ceilings, while leaving your hands free.

Werewolf Claws

You grow razor-sharp claws from your fingers. These claws are a natural weapon which counts as a simple melee weapon with which you are proficient with. You can use either Strength or Dexterity for the attack and damage rolls for these claws, and they deal 1d6 slashing damage on a hit. They also count as magical for the purpose of overcoming resistabce and immunity to nonmagical attacks and damage.

When you attack with the claws using the Attack action, you can make one more additional attack with them as a bonus action. 

Hybrid Endurance

Also at 3rd level, your mutations allow you to withstand certain types of harm. Choose one option from the Hybrid Endurance list. You gain resistance to certain damage types based on your choose, and you can choose another option at 18th level.

Celestial Constitution

You have the blessing of a celestial coursing through your veins. You gain resistance to force and radiant damage.

Elemental Constitution

You have the essence of an elemental coursing through your veins. You gain resistance to lightning and thunder damage.

Fey Constitution

You have the spirits of the Fewild coursing through your veins. You gain resistance to acid and psychic damage.

Fiendish Constitution

You have the blood of a fiend coursing through your veins. You gain resistance to fire and cold damage.

Undead Constitution

You have the curse of an undead entity coursing through your veins. You gain resistance to necrotic and poison damage.

Mutated Senses

At 7th level, your eyes or other senses go through a quickened evolution. Choose one option from the Mutated Senses list. You gain the benefits of that mutation, and can choose another option from the Mutated Senses list when you reach 15th level.

Devil's Sight

You can see normally in darkness, both magical and nonmagical, to a distance of 120 feet. If you already have darkvision, extend it out to an additional 120 feet.

Eldritch Sight

You can cast detect detect magic at will.

Hag's Sight

You can cast see invisibility on yourself. You can’t do so again until you finish a short or long rest.

Keen Senses

You gain proficiency in the Perception skill if you don't already have it, and your proficiency bonus is doubled for any ability checks that use this skill.

Telepathic Mind

You can telepathically speak to any creature you can see within 60 feet of you. You don’t need to share a language with the creature for it to understand your telepathic utterances, but the creature must be able to understand at least one language.

Mutated Organs

At 10th level, our internal organs are transformed to give you supernatural abilities. Choose one option from the Mutated Organs list. You gain the benefits of that mutation, and can choose another option from the Mutated Organs list when you reach 18th level.

Daunting Roar

As a bonus action, you can let out an especially menacing roar. Creatures of your choice within 30 feet of you that can hear you must succeed on a Wisdom saving throw or become frightened of you until the end of your next turn. The DC of the save equals your Mutation save DC. If a creature succeeds this saving throw, they are immune to being frightened of you for 24 hours.

You can use this feature a number of times equal to your proficiency bonus, and all expended uses are restored when you finish a long rest.

Deathless Nature

You don’t need to eat, drink, or breathe.

Dragon's Breath

When you take the Attack action on your turn, you can replace one of the attacks with an exhalation of draconic energy in either a 20-foot cone or a 30-foot line that is 5 feet wide (your choice). Choose a damage type: acid, cold, fire, lightning, or poison. Each creature in the area must make a Dexterity saving throw against your Mutation save DC, taking 3d8 damage of the chosen type, or half as much damage on a success.

You can use this feature a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.

Heart of Regeneration

At the start of each of your turns, you regain hit points equal to 1 + your Constitution modifier (minimum of one) if you have at least 1 hit point and no more than half of your hit points left.

Storming Breath

As an action, you can cast gust of wind using only your breath. Constitution is your spellcasting ability for this spell. Once you cast it once, you can't cast it again until you finish a short or long rest.

Mutated Skin

At 15th level, your skin develops a feature to give you an advantage in any battle. Choose one option from the Mutated Skin list. You gain the benefits of that mutation.

Changeling's Skin

You can cast the alter self at will.

Dragon's Hide

You gain resistance to bludgeoning, piercing, and slashing damage from nonmagical weapons.

Hardened Shell

When you are hit by an attack, you can use your reaction create a temporary exoskeleton over your skin. Until the start of your next turn, you can add 1 + your Constitution modifier (minimum 2) to your AC.

Shroud of Shadow

You can cast the invisibility spell at will.

Tempest's Protection

When you are hit by a melee attack, you can use your reaction to deal lightning damage to the attacker. The damage equals your fighter level. The attacker must also make a Strength saving throw against your Mutation save DC. On a failed save, the attacker is pushed in a straight line up to 20 feet away from you.

Apex Warrior

Starting at 18th level, your reflexes or willpower improves to extraordinary levels. When you make a saving throw using any ability score, you can treat a d20 roll of a 9 or lower as a 10.