Physical Mutations

Physical mutations are changes to the frame: limbs, hide, organs, gait, glands, and the speed at which a wound closes. They are ordinary biology. They keep working in a miasma-dead zone, and nothing that Dispels or Counters a Protocol can touch them. Where an ability would normally need a weapon, a tool, or a suit of armor, the mutation grows the organ that does the same work -- a claw, a spine, a plate of chitin, a venom duct.

Frame and locomotion

MutationEffectNotes
SpeedYour base speed increases by 10 ft. When you Dash, difficult terrain costs you nothing that turn. When you make a melee strike against a creature, you do not provoke an opportunity attack from it for the rest of the turn.--
Sure-LimbedIncrease STR or DEX by 1. Standing from prone costs only 5 ft of movement. Climbing costs no extra movement. You can make a running jump after moving only 5 ft on foot.--
ChargeIf you move at least 10 ft straight toward a creature and then hit it with a melee strike, you deal an extra 1d8 damage or push it 10 ft.--
Reach LimbYou grow an elongated limb or tail with 10 ft of reach. A creature that enters your reach provokes an opportunity strike from it. After you make a melee strike, you can make one bonus blunt strike (1d4) with the limb.--
Symbiont BondYou can fuse to a larger willing creature as a living rider. While joined you direct its movement; attacks aimed at it can be redirected to you; and it takes no damage when it succeeds on a DEX save against an effect that deals half on a success.--

Natural weaponry (melee)

MutationEffectNotes
Natural WeaponryYou bear more than one set of natural weapons. When you make an extra natural-weapon strike as a bonus action, add your ability modifier to that strike's damage.--
Many-LimbedWhile you fight with two natural weapons you gain +1 AC. Your off-limb strikes can use a larger damage die, and readying your limbs never costs an action.--
Living WeaponYour unarmed and natural strikes deal 1d6 damage (1d8 if you have no other natural-weapon mutation). A creature you grapple takes this damage at the start of each of its turns.--
BrawlerIncrease STR or CON by 1. Your natural strike deals at least 1d4 and you reroll a 1 on its damage. When you hit with it, you can grab or shove the target as part of the same action.--
Singular FocusWhen you attack with a single natural weapon and bear no other, you gain +2 to that weapon's damage.--
Brutal FrameWith a heavy two-handed natural weapon, once per turn on a hit you can take a -5 penalty to the attack for +10 damage. When you score a critical hit or drop a creature to 0 HP, make one bonus strike.--
Heavy FrameWith a heavy natural weapon, treat any 1 or 2 rolled on its damage dice as a 3.--
BonecrusherIncrease STR or CON by 1. Your bludgeoning strikes can push a target 5 ft. Once per turn, a critical hit leaves the target vulnerable -- attackers have advantage against it until your next turn.--
ImpalerIncrease STR or DEX by 1. Once per turn you can reroll one piercing damage die. On a critical hit you deal one extra damage die.--
RenderIncrease STR or DEX by 1. Your slashing strikes reduce the target's speed by 10 ft until your next turn. On a critical hit, the target has disadvantage on attacks until your next turn.--
Grasping LimbsYou have advantage on attacks against a creature you grapple. You can spend an action to pin a grappled creature, leaving both of you restrained until the grapple ends.--
VenomIncrease DEX or CON by 1. Your natural weapon delivers poison, and your poison ignores resistance. Once per long rest you can expel a poison cloud (15-ft cube; each creature makes a CON save or is poisoned for 1 minute).--

Ranged and projectile organs

MutationEffectNotes
True AimYou grow an organ that fires natural projectiles (spines, spit, seeds). You gain +2 to attack rolls with ranged natural weapons.--
Keen StrikeYour ranged projectiles ignore half and three-quarters cover and have no penalty at long range. Once per turn you can take a -5 penalty to the attack for +10 damage.--
Rapid SpitterFiring a projectile at a creature within 5 ft is not at disadvantage. When you take the Attack action with your projectile organ, you can make one bonus projectile strike.--
LauncherYou can grow and hurl heavy organic projectiles. You gain +2 damage with thrown natural weapons, and producing one for the throw costs nothing.--

Hide and carapace

MutationEffectNotes
CarapaceA layer of natural armor grants +1 AC.--
HideIncrease STR or DEX by 1. A thickened hide grants +1 AC and never interferes with stealth.--
PlatingYour medium natural armor lets you add up to +3 of your DEX bonus to AC, and it never imposes disadvantage on stealth.--
Dense CarapaceIncrease STR or CON by 1. Reduce the bludgeoning, piercing, and slashing damage you take by 3.--
Bulwark LimbYou grow a broad, hardened limb or frill. As a bonus action you can shove with it. Add its bulk to DEX saves against effects that target only you; when you succeed on such a save, you take no damage instead of half.--

Reflex and defense

MutationEffectNotes
Threat ReflexWhen you hit a creature with an opportunity strike, its speed drops to 0 for the rest of the turn. Creatures provoke opportunity strikes from you even when they Disengage. When a creature within reach attacks someone other than you, you can strike it as a reaction.--
Guardian ReflexWhen a creature you can see attacks a target within 5 ft of you, you can use a reaction to impose disadvantage on the attack.--
InterposeWhen a creature within 5 ft of you takes damage, you can use a reaction to reduce that damage by 1d10 plus your modifier.--
Parrying SpursWhen a melee attack hits you, you can use a reaction to add your proficiency bonus to your AC against it, possibly turning the hit into a miss.--
EcholocationYou gain blindsight to 10 ft. Within that range you ignore the effects of being unable to see and of attackers being unseen.--
LurkerYou can try to hide even when only lightly obscured. Missing with a ranged strike does not reveal your position. Dim light does not impose disadvantage on your Perception checks that rely on sight.--

Resilience and recovery

MutationEffectNotes
HardyYour HP maximum increases by 2 for each level you have, and by 2 more each time you gain a level.--
RegenerativeIncrease CON by 1. When you spend a healing die, treat any roll lower than the die's average as the average. You stabilize on your own when dying.--
TemperedIncrease one ability by 1 and gain proficiency in saving throws made with it.Repeatable (different ability each time)
Mending SecretionYou secrete a healing agent. With a touch you can halt a dying creature's decline and restore a small amount of HP, a number of times equal to your proficiency bonus per long rest.--
Nourishing SecretionYou produce a nourishing substance. Allies who take it in during a short or long rest gain temporary HP and shed one level of fatigue.--
Shaping LimbsYour limbs can improvise tools and reshape raw matter directly. You have advantage on checks to build, repair, or reshape objects, and you need no outside tools to do so.--