Core Trait: 

Your body rapidly evolves in response to stimuli. You have 8 use/charges of this trait before it expires, It only restocks after you finish a short or long rest. choose one adaptation from the list below.

Projectile: gain half resistance of all projectiles used on user before this adaptation use. complete resistance is given to all projectiles half adapted to.

Crush: if move against creature fails due to armor class, block, or any defensive move, after this adaptation player can ignore effect of said stimuli.

Chase: User gains additional movement speed is equivalent to half the distance of target , after this adaptation is used.

Effect: if user has effect/condition active and if this adaptation is used they gain immunity to all effects active prior to the adaptation.

Grapple: if user is grappled or some how restrained, this adaptation renders all active grabs or restrains useless during adaptation or prior to it.

Tank: user gains +1 armor class per Tank adaptation and Advantage on one physical saving throw type (Str/Dex/Con)

Recovery:  if this adaptation is used, effect activates, user gains passive healing 1d10 per turn, but if any adaptation is made after it cancels this effect.

Sensory: if adaptation is used gains: Blindsight, True Seeing, Tremorsense and keen senses. The effect increases by 50% every Sensory adaptation use.

Move: gain half resistance of all moves/spells/traits used on user before skill use. complete resistance is given to all moves/spells already half adapted to.

 all adaptations the user has made will reset after a short/long rest, but you have a chance to keep 4 adaptations for this short/long rest if you roll 1d20 and go above 10*

Restore Adaptive Genome 8 charges, Once per long rest, as a bonus action.

Increase movement speed, stats, and moves/spells by 25%, also gains resistance to biome effects by the percentile e.g skill use in snowy biome gain ice resistance. increase by 50% if used while on 5% of hit points,. or by 100% if use after death saving throw. on use of this trait user copies and saves a move, spell, skill, or trait of last fought creature.

trait can be used once per Long rest but if fail to long rest it moves up to a day.*

Use the Adaptive Genome skill as a reaction, or bonus action. This can be use 3 times before the needing to take a Long rest to reuse this trait

Your mastery of copied techniques allows you to reverse them.

Whenever you use an ability gained through Evolutionary Growth, you may invert its effect.

Examples include:

The inverted version must remain roughly equal in power to the original effect.

The DM determines the final outcome if no clear opposite exists.

As a bonus action, you may alter your body by developing one permanent biological trait. This transformation changes both your physiology and appearance to reflect the chosen adaptation.

The trait grants an appropriate mechanical benefit determined by the the user and must be based on a real or theoretically plausible biological adaptation found in nature or reasonably extrapolated from it.

Examples

• Prehensile Tail. You grow a muscular tail capable of grasping objects. You gain advantage on ability checks made to maintain balance, and the tail can manipulate unattended objects, hold equipment, or perform simple interactions.
• Climbing Claws. Gain a climbing speed equal to your walking speed while your hands are free.
• Gills. You can breathe underwater.
• Night Vision. You gain darkvision out to 60 feet.
• Protective Carapace. Your skin hardens, granting a +1 bonus to AC while you aren't wearing heavy armor.
• New Organs. to enhance or preform features passively

Biological Limitations

Your adaptations must obey the limits of biology. A chosen trait must have a believable anatomical basis and cannot grant abilities that require supernatural or magical phenomena.

The following are not valid choices:

• Eye lasers or other energy projection.
• Flight without wings or another believable means of generating lift.
• Telepathy, invisibility, or other magical effects.
• Violating the laws of physics or the four fundamental forces.

If there is any doubt whether a proposed adaptation is biologically plausible, the DM has the final say.

A biological trait should enhance what your body can naturally do—not allow it to perform impossible feats.

also any biological trait that can be found on earth is automatically verified but you must say which animal, part or trait, and where on your body(only two parts can occupy the same space)(can be on entire body if original animal has it throughout it)*

Metamorphosis Energy —

Your body possesses a pool of Metamorphosis Energy (ME). This represents the biological resources required to create, maintain, and activate your adaptations.

Your maximum Energy is:

Maximum ME = 5 + Proficiency Bonus + Character Level

But each adaptation has an Adaptation Tier that determines its cost.

A Tier I adaptation isn't merely 1/16th as useful as a Tier VI adaptation. Higher tiers represent increasingly complicated changes to your entire physiology.

the player doesn't get to decide the Tier just because they want it to be cheap. The DM/user determines the biological complexity and power of the adaptation if it doesn't already exist if and both player and DM is confused feed this traits information and new part into an AI for an non-biased observation.

Biological Power Modifier

If the adaptation is significantly stronger than a normal example of the trait, increase its cost.

The default/base power of any trait that can be found on earth is relative to the animal it's derived from, meaning it doesn't stay how strong it actually is how strong it is in it's base(e.g house spider venom, rather than be an irritant it is paralyzing)

Modification levels: are stages of upgrades the player can make to the base part to make it stronger, every stage level up is 10% effect boost

So:

Normal Prehensile Tail

Tier II → 2 ME

Extremely strong prehensile tail

Tier II + Highly Enhanced → 4–5 ME

Normal wings

Tier III → 4 ME

Extremely powerful wings

Tier III + Extreme → 8–10 ME

This prevents someone from exploiting the system by saying:

"It's just a tail, so it's only Tier II."

while giving the tail enough strength to function like a superpowered limb.

Scaling With Level

Your Energy pool should increase roughly like this:

This gives you a useful progression:

Low level:
You can afford several small adaptations or one significant adaptation.

Mid level:
You can maintain a collection of sophisticated biological features.

High level:
You can create extremely powerful adaptations, but they still consume a substantial portion of your Energy pool.

Level 20:
30 ME sounds enormous, but a 22+ ME Apex adaptation can still consume most of your entire pool.

The Core Rule

The more powerful an adaptation is, the more Energy it requires.

The Energy cost of an adaptation is determined by the total biological complexity, physical capability, and number of biological systems affected. Minor adaptations are inexpensive, while adaptations approaching the limits of natural biology require increasingly large amounts of Energy. Also every time the trait/part is in use or activated it uses energy per use

You cannot reduce the Energy cost of an adaptation simply because your character has reached a higher level.

That last sentence is important.

Your character gets more Energy, rather than powerful traits becoming cheap.

So your progression looks like:

Level 1:
6 ME → several minor traits.

Level 10:
17 ME → multiple advanced traits.

Level 20:
30 ME → several extreme traits OR one Apex adaptation + several smaller ones.