Ancient Dragon-Dragon Fruit: Model Ankylosaur

Animal Transformation: As an action on your turn you can transform into an ankylosaur. Any items being worn or carried can be assimilated into the new form. Spells that require somatic components cannot be cast while in this form. While in this form you do not benefit from armor you were wearing prior to transforming. You retain your Intelligence, Wisdom, and Charisma scores if they are higher than that of an ankylosaur. You can use a bonus action to revert to your normal form. When you revert to your normal form, you return to the number of hit points you had before transforming. However, if you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form. When this happens, you cannot transform fully again for 1d4 hours.
Hybrid Form: You may use a bonus action on your turn to transform a distinct part of your body into that of an ankylosaur(growing dinosaur skin, transforming a limb to escape bindings, changing the sound of ones voice using dinosaur windpipes, etc.). You gain two sub-abilities which can each only be used after activating Hybrid Form and growing the specific body parts involved:

Club Tail- As an action you may use your tail to make an unarmed attack against a single target within 5ft. of yourself. You are not proficient with the club tail weapon at this level of mastery. On a hit, the club tail attack deals 2d6 bludgeoning damage.
Armored Skin- Your AC increases by 1.

Animal Aspect: You gain +2 to your Strength and Constitution scores(up to a maximum of 20).
Bestial Vitality: Once per long rest, you may use a bonus action on your turn to regain 4d6 hit points instantly. When you take a short rest, you gain an extra pool of hit dice equal to your proficiency modifier(does not stack). After each rest(short or long) you gain a pool of temporary hit points equal to 3 times your proficiency modifier. This pool of health remains until it is depleted or you take another rest, at which point the pool is refreshed.

Improved Animal Transformation: You may now use a bonus action to fully transform. When fully transformed you gain resistance to nonmagical bludgeoning, piercing, and slashing damage. You are now proficient with your tail attack when fully transformed.
Improved Hybrid Form: When you hit an attack with your club tail the target of that attack must make a DC16 Strength saving throw. On a failed save, roll a d4 and consult the table below to determine the effect. *A target cannot be affected by more than one of these effects at the same time. When you hit an attack against a target with your tail club, you can also attempt to hit any other viable targets within 5ft. of yourself, rolling a separate attack for each target. You only roll on the below table once per attack, applying the same effect to all hit targets. When you choose to grow armor, your AC now increases by 2.

Roll	Effect
1	Target is knocked prone.
2	Target is driven into the nearest surface, restraining it within and creating a sizable hole in the surface.The target can use its action on its turn to remove itself from the surface and end the effect.
3	Target is knocked back 1d4x5ft.
4	Target cannot take reactions until the start of its next turn.

Improved Animal Aspect: You are now proficient in Strength and Constitution saving throws.
Improved Bestial Vitality: When taking a short rest, you now heal the maximum amount for each hit dice spent.
Shell Shanker: Your armored hide can now sprout sharpened spikes or cuticles that can hurt attackers. When you are fully transformed and a creature makes a melee attack against you, that creature must roll a D20. On a 5 or lower, that creature takes 2d8 piercing damage if its attack hits you. This ability does not apply to melee attacks made with weapons posessing the reach property.

Advanced Animal Transformation: You may now fully transform using a free action on your turn. When fully transformed you now have immunity to all nonmagical bludgeoning, piercing, and slashing damage. When fully transformed, your tail attack now deals 4d8 bludgeoning damage on a hit.
Advanced Hybrid Form: When at least half of your body is transformed you gain resistance to nonmagical bludgeoning, piercing, and slashing damage. When you choose to grow armor your AC now increases by 3. You may now add your proficiency modifier to attacks made with your club tail, and you now deal 4d6 bludgeoning damage on a hit with it. The save DC for targets struck by your tail club increases to 18.
Advanced Animal Aspect: You now have advantage on all Strength and Constitution saving throws.
Advanced Bestial Vitality: You can make use of Bestial Vitality a number of times per long rest equal to half your proficiency modifier(rounded up). You now heal for 6d8 hit points when using Bestial Vitality.
Advanced Shell Shanker: Your Shell Shanker ability now activates when a target rolls a 10 or lower, and deals 4d8 piercing damage on a hit. You can make use of your Shell Shanker ability in your Hybrid form.

No image of this fruit exists(yet).