Blood Crystal Dragon

Resistance to Energy: You have resistance to one type of energy damage (acid, cold, fire, lightning, poison, or thunder) determined by the color of your blood crystal.

Blood Crystal Weapon: can create a weapon made of blood crystal as a bonus action. The weapon can take the form of any melee weapon with which it is proficient. The weapon deals slashing or piercing damage (your choice) and has the finesse and thrown properties. The weapon has a +1 bonus to attack and damage rolls and lasts for one minute. You can use this ability once per long rest.

Blood Crystal Surge: Once per long rest, you can use your Blood Crystal Surge ability to gain an additional spell slot of your highest level for one hour. When you use this ability, you must make a Charisma saving throw (DC 10 + the level of the spell slot) or take damage equal to the level of the spell slot you gained.

Crystal Scales: Your scales are infused with the power of your blood crystal, giving you a natural armor class of 13 + your Dexterity modifier. Additionally, you have advantage on saving throws against being paralyzed or stunned.

Blood Crystal Blast

3rd-level Evocation

Casting Time: 1 action

Range: Self (30-foot cone)

Components: V, S

Duration: Instantaneous

As it exhales, a cone of crystalline shards shoots forth from its mouth. Each creature in a 30-foot cone must make a Dexterity saving throw. On a failed save, a creature takes 5d6 piercing damage and 2d6 force damage, and is knocked prone. On a successful save, a creature takes half as much damage and is not knocked prone.

At Higher Levels. When it cast this spell using a spell slot of 4th level or higher, the piercing damage increases by 1d6 for each slot level above 3rd.

Crystal Shard Barrage: You can use a bonus action to release a barrage of sharp crystal shards at one creature within 60 feet of you. Make a ranged spell attack against the target. On a hit, the target takes 2d6 piercing damage and must make a Dexterity saving throw or take an additional 1d6 piercing damage on its next turn.

Blood Crystal Burst: You can use a bonus action to release a burst of magical energy from your blood crystal, dealing 2d8 force damage to all creatures within 10 feet of you. Any creature that takes damage from this ability must also make a Constitution saving throw or become stunned until the end of its next turn.

Blood Crystal Glide: You can use a bonus action to transform your wings into a semi-solid state and glide a short distance. You gain a fly speed of 30 feet for one round, but must end your movement on solid ground or fall.

Crystal Spike: You can use a bonus action to create a sharp crystal spike from the ground beneath a creature within 30 feet of you. The target must make a Dexterity saving throw or take 2d6 piercing damage and become restrained until it takes an action to break free.

Blood Crystal Shield (Reaction)

Prerequisite: The blood crystal dragon must have at least one unused spell slot of 1st level or higher.

As a reaction to being attacked by a creature within 30 feet, the blood crystal dragon can use its innate magical ability to create a shield made of blood crystal. The dragon expends a spell slot of 1st level or higher to create the shield, which lasts for one minute.

The shield has hit points equal to twice the level of the spell slot expended, and it has a hardness of 10. While the shield is active, the blood crystal dragon gains a +2 bonus to its AC. Additionally, the shield grants resistance to one damage type of the blood crystal dragon's choice, which is determined when the shield is created.

If the shield is destroyed before the duration expires, the blood crystal dragon takes psychic damage equal to the level of the spell slot expended. If the blood crystal dragon is reduced to 0 hit points while the shield is active, the shield explodes, dealing 6d6 force damage to all creatures within 20 feet of the dragon.

Enter the description for how legendary actions work for your monster here.

Legendary Action Name (Costs # Actions). Enter the description for your legendary action.

Crystal Shard Storm: You can use a mythic action to summon a storm of sharp crystal shards that swirl around you. All creatures within 30 feet of you must make a Dexterity saving throw or take 4d8 piercing damage.