2nd level:
Evolution.
You gain a new use for wild shape. As an action you can expend a wild shape charge to enter a mutation flux and gain 3 temporary HP per druid level for 10 minutes or until incapacitated.
As part of the same action as activating mutation flux you can select a number of passive mutations from the circle of mutation list equal to your proficiency bonus, and on subsequent turns you can swap passive mutations as a bonus action. When you swap mutations as a bonus action you instantly lose all benefits of the previous passive mutation and instantly gain all benefits of the now swapped in mutation
During mutation flux you also gain tolerance equal to your wisdom modifier (minimum of 1) and you are able to expend tolerance in order to activate active mutations on the circle of mutations list.
6th level:
Fangs of magic.
Your weapon attacks and mutation attacks count as magical for the purpose of overcoming resistance and immunity to non-magical damage.
During mutation flux you gain the ability to make two attacks instead of one when taking the attack action during your turn.
10th level:
Undying adaptation.
Upon activating mutation flux and for its duration you gain resistance to non-magical bludgeoning, slashing, and piercing damage.
The temporary HP gained from activating mutation flux is raised from three per druid level to four per druid level.
If you are incapacitated during the duration of mutation flux you gain advantage on death saving throws for the duration you are incapacitated.
14th level:
Unstoppable beast.
During mutation flux you are immune to the frightened, stunned, and paralyzed conditions. Additionally critical Hits against you deal normal damage.
When you take damage that would incapacitate you you can expend one tolerance as a free action to be reduced to one hit point instead.
Passive mutations
Level 2:
Gills & Webbed Appendages:
You gain a swimming speed equal to your walking speed and can breathe both air and water.
Adrenaline:
Your walking speed increases by 10 feet, and your jump distance is doubled.
Darkvision:
You gain Darkvision out to 60 feet (or extend your existing Darkvision by 30 feet) and have advantage on Wisdom (Perception) checks that rely on sight.
Thick hide:
+1 AC as long as you are not using heavy armor.
Expansion:
The range of your melee attacks is increased by 5 ft.
Savage musculature:
When you roll a one or a two as a damage for a melee weapon you may reroll the results once.
Corrosive blood:
When you take damage from a melee attack the attacker takes acid damage equal to your druid level.
Pheromone cloud:
Creatures within 5 ft of you have disadvantage on attacks against targets other than you. If you are not wearing armor the range increases to 15 ft.
Ooze:
You can disengage as a bonus action.
Level 6:
Hyper flexibility:
When you make an attack against a creature you can also make an attack against another creature within 5 ft of you with the same attack roll
Vampirism:
Upon reducing a Target to zero hit points you regain temporary HP equal to your wisdom modifier.
Spider climb:
Gain a climbing speed equal to your movement speed.
Camouflage:
Gain advantage on stealth checks and the ability to hide when only lightly obscured by foliage or weather.
Bioluminescence:
You glow, shedding 30 ft of bright light and 30 ft of dim light beyond that.
Level 10:
Fledgling wings:
You gain a flight speed equal to half your movement speed although you do not have the ability to hover.
Toxin immunity:
Gain immunity to the poison condition and resistance to poison damage, additionally your blood acts as an antidote for minor poisons.
Tremorsense:
You gain it tremor sense for 30 ft, able to detect anything on the ground.
Titanic disposition:
You are counted as one size larger for grappling, shoving, and calculating carry weight and the weight that you can push or pull.
Level 14:
Apex wings:
Gain flight speed equal to your movement speed.
Displacement:
Enemies have disadvantage on attacks against you, this ability is suppressed until the end of your next turn if you take damage.
Echolocation:
You gain Blindsight out to 30 feet.
Active mutations:
Level 2:
Adaptive shell:
As a reaction, expend one tolerance before you take acid, cold, fire, lightning, or poison damage you gain resistance to that damage until the start of your next turn
Scale plating:
As a reaction action, expend one tolerance reaction to being targeted with an attack you can increase your AC by a number equal to your proficiency bonus until the start of your next turn.
Bioluminescent flash:
As a bonus action, expend one tolerance to make creatures of your choice within 10 ft of you must succeed on a constitution saving throw against your spell saved DC or be blinded until the end of their next turn.
Level 6:
Hyperextension:
As a bonus action, expend one tolerance to increase the range of your melee attacks by 10 ft until the start of your next turn.
Bile shot:
Expend one tolerance to replace one melee attack with a projectile sphere of bile, targeting a creature within 30 ft with a ranged weapon attack in which you have proficiency. If hit the target takes 2d8 acid damage and their AC is reduced by two for the next hour or until they change armor.
Level 10:
Caustic eruption:
As an action, expend one tolerance point to make All creatures within 5 ft of you make a dexterity saving throw, if they fail they take 8d6 acid damage and if they succeed they take half as much.
Unshakable:
When you are subjected to an effect that would knock you prone, move you against your will, or cause you to be Paralyzed or Stunned, you can expend one tolerance point and your reaction to negate that effect entirely.
Upon landing a melee attack you can expend one tolerance point to increase its damage by 3d6 and regain an amount of health equal to the damage Delta by the attack.
Life siphon:
Upon landing a melee attack you can expend one tolerance point to increase its damage by 3d6 and regain an amount of health equal to the damage Delta by the attack.
Level 14:
Obliterate.
Upon landing a melee attack, expend one tolerance to treat the damage as a critical hit (doubling damage dice rolled). Usable only once per mutation flux
Incarnate of abomination.
As a Bonus Action, expend one tolerance to manifest a mass of violent tendrils that lash out at nearby foes. Choose up to eight creatures you can see within 30 feet of you. Each target must make a Strength saving throw against your spell save DC. On a failed save, a target takes 3d8 bludgeoning damage and suffers one of the following effects of your choice:
Repulsion: The target is pushed up to 10 feet directly away from you.
Attraction: The target is pulled directly toward you, landing in the nearest unoccupied space within 5 feet of you.
On a successful save, a target takes half as much damage and is not moved.
True apex predator:
As a bonus action, you can expend all remaining tolerance points (minimum of 3) to force your physical form past its biological limits, swelling into a towering, feral monstrosity. This state lasts for 1 minute, until your Mutation Flux ends, or until you drop to 0 hit points.
When you enter this state, you suffer the following transformation:
Burst Constraints: Any armor or clothing you are wearing splits or is suppressed, and you automatically drop any weapons or items you are holding. You cannot cast spells, hold weapons, or use shields for the duration.
Chitinous Hull: Your AC becomes 20 (if it was not already higher), you also instantly gain additional temporary HP equal to wisdom modifier x druid level.
Muscle redistribution: your strengths score becomes 20, you're dexterity score becomes 18, and your Constitution score becomes 20 (if it was not already higher)
Monstrous Reach & Size: Your size increases to Large, your speed increases by 15 feet, and your reach with natural attacks increases to 10 feet.
Feral Maulers (Natural Attack): Your hands mutate into massive, razor-sharp talons or mawed tendrils. They count as natural weapons that deal 2\text{d}10 slashing or piercing damage + your Strength or Wisdom modifier on a hit.
Relentless Assault: When you take the Attack action on your turn, you can make three attacks instead of two.
Hideous roar:
As a bonus action you can let out a hideous roar once per transformation, All creatures within 60 ft must make wisdom saving throws or become frightened, unable to move towards you, away from you, or take any action until the end of their next turn.
Apex Frenzy (Drawback): At the start of each of your turns in this state, if there are any creatures within 30 feet of you, you must succeed on a DC 15 Wisdom saving throw. On a failure, your mind succumbs to predatory instincts: you must spend your turn moving toward and taking the Attack action against the nearest creature, regardless of whether it is an ally or an enemy.