Mutations

Mutations are extra abilities that are given to you at the end of a level if you have leveled up. To level up, you need to get 60 Rads multiplied by your current level number, which means the amount of Rads required increases with the character's level (60, 120, 180, etc.). Each level up is signified by a white crown symbol appearing above your character. Going over level 9 and essentially reaching level 10 (Level Ultra) allows you to choose one of the character-specific Ultra Mutations listed below the regular Mutations table.

Mutations table

A list of all the mutations in alphabetical order. At the end of a level, you can choose between 4 randomly-rolled mutations per level up. Currently, the game allows players to reach level 10, which means a total of 9 mutations (or 10 mutations if you take the Crown of Destiny, 11 if you also picked Patience).

In Co-op, picked mutations will affect both characters.

Mutation	Icon	Description
Back Muscle		Bullet capacity increases from 255 to 555 and all other ammunition's capacity increases from 55 to 99.
Bloodlust		Gives you a 7.69% (1/13) chance of regenerating 1 HP when you kill an enemy.
Boiling Veins		You take no damage from explosions or flames when at 4 or less HP. To clarify; if you are damaged by fire or an explosion at 4 HP or above, you will end up with no less than 4 health, and as such you can no longer be killed by either kind of attack or hazard. Boiling Veins also makes explosions unable to damage the player during their hurt animation, regardless of their current HP. In other words, you can't be hit by more than one explosion at once, and all explosion damage is essentially halved (normally, explosions deal 5-10 dmg; with Boiling Veins, they can only deal up to 5). If your max HP is already 4 or less, such as when playing as Melting without Rhino Skin or as Chicken after dying and resurrecting too many times, Boiling Veins will grant full immunity to fire and explosions as expected.
Bolt Marrow		Bolts and splinters seek enemies, changing their direction if close enough. Larger bolts from Heavy Crossbows will have a weaker homing effect. Seekers will home from further away, and take much sharper angles. Discs slightly attract toward enemies and slow down to hit an enemy multiple times.
Eagle Eyes		Increased accuracy; shot spread is reduced to 70%. Reduces fixed spread for weapons like the Triple Machinegun, Shotgun, Super Slugger, Super Crossbow, Splinter, and Seeker weapons, as well as the Shovel. As a result, their projectiles are grouped tighter together. Steroids' accuracy will be boosted to a level a bit beyond the other mutants' base accuracy, but it will still not be as much as the other mutants with Eagle Eyes.
Euphoria		Reduces enemy projectile speed by 20%. Synergizes well with Eyes's active ability.
Extra Feet		Movement speed is increased. Additionally makes you walk normally on all floor tiles, such as spider webs in Crystal Caves and ice in Frozen City.
Gamma Guts		Touching enemies makes them take 6 damage per tick for as long as your character is in contact with them. You will take no contact damage from enemies that have less than or equal to 12 HP at the moment of impact, but only while moving. Otherwise, you'll only be protected from enemies that have 6 or less HP. For example, Rats start with 7 HP and will instantly die from touching you while you are moving, but can still damage you if they make contact with you while you remain stationary. If an enemy is killed by Gamma Guts, your character will create an area of effect blast which deals 8 damage to all nearby enemies. Synergizes well with Scarier Face, which, when combined with Gamma Guts, can let you kill Snowbots simply by walking into them. Gamma Guts can also be used as a last resort if you run out of ammo and don't have a melee weapon or alternative means of attack.
Hammerhead		Pushing against a wall allows your character to break through them, which is useful to create instant cover, bypass troublesome level geometry, or ambush enemies. You can also break Fire Traps by walking into them. You can only break 20 wall tiles at most per level; this limit is reset each time you go through a level ending portal.
Heavy Heart		The rate of weapon drops from enemies is increased by 210% (applied multiplicatively to the base odds). The Maggots Nest, for example, has a 35% chance to spawn a weapon. With Heavy Heart, that becomes 73.5% (0.35 * 2.10 = 0.735). This mutation is not a part of the usual mutation pool. Heavy Heart will only appear after you've picked your third "Weapon-Specific" mutation and won't appear again. These mutations are Recycle Gland, Shotgun Shoulders, Bolt Marrow, Boiling Veins, Laser Brain, and Long Arms.
Impact Wrists		Makes corpses fly much farther and faster, and they deal more damage on impact.  Normally, a corpse does 1 base damage on impact with an enemy, but with this mutation, they deal 2 base damage.
Laser Brain		Energy weapons have the size and/or duration of their attacks increased so they last longer and can hit a target more times. Lasers last longer by getting wider, dealing 2-14 damage.  Additionally, the Laser Cannon fires two more beams, as the burst charge lasts longer. Plasma balls get bigger and can hit 2 extra times. Normal plasma deals 4-22 damage, big plasma (i.e; Plasma Cannon) deals 17-83 damage, and huge plasma (i.e; Super Plasma Cannon) deals 28-139 damage. Plasma Explosion damage doesn't change, but the Devastator projectile travels 40% slower, letting it hit more often and create more plasma explosions. Lightning rails last longer, dealing 7-21 damage. The Lightning Cannon projectile's impact damage is also upped to 50. Energy Melee slashes and shanks last twice as long, so they can hit enemies twice. Energy melee can also travel farther due to it lasting longer.
Last Wish		Choosing this mutation will fully heal your character and give you 200 bullet ammo, plus 20 ammo for every other type. It also fills Rogue's Portal Strike ammo. Chicken will replenish all of her lost max HP when choosing this mutation. You can also revive Chicken by picking Last Wish while she's headless inside a portal. Taking this mutation will uncurse any Cursed Weapons the player was holding. After picking Last Wish, the Frozen Corpse Flower will appear in the first level of Frozen City. Entering the Jungle secret area via the flower by feeding it 4 of your HP will remove Last Wish from your character's mutations. You will instantly choose a mutation that replaces it; the mutations will be a completely fresh set as if you had taken Patience. Last Wish will be put back into the pool of mutations you can choose from, so it's possible to pick it again from this set.
Long Arms		More melee range. Melee swings will spawn and travel further from the character.
Lucky Shot		Killing an enemy has an 11.76% (2/17) chance to give a random ammo type, with the amount being one Ammo Pickup's worth of ammo. Due to this, Fish gets more ammo from Lucky Shot than other characters.
Open Mind		An extra Ammo Chest, Weapon Chest, or Radiation Canister will spawn on every level, with equal chances of appearing. Extra Chests/Canisters can appear in different forms, depending on the conditions and chances listed on the Pickups page. Chests that appear only in Secret Areas can also spawn as extras in those areas. If two Weapon Chests spawn on the same level and you leave both unopened, both will count towards spawning a Large Weapon Chest. If two Radiation Canisters spawn on the same level and you leave both unopened, they will count as one Big Radiation Canister. Playing as Rogue changes the extra Radiation Canisters into Portal Strike Ammo Canisters.
Patience		This acts as a re-roll for the current set of mutations. By itself, it has no effects, but the next time you enter a portal, you will get another set of four mutations to choose from. Patience itself doesn't count towards the mutations cap, which means you can technically have 9 mutations at max level (10 with Crown of Destiny). Patience actually skips to the next selection of mutations, meaning that no matter if you pick Patience or another mutation on offer, the next level-up has the same set of mutations. This only has a practical effect in seeded runs like the Daily Run, though.
Plutonium Hunger		Increases the pick-up range for attractable pickups like Rads, Ammo Pickups, and HP Pickups. Rads have a bigger increase in attraction range than other pickups do. Since Cursed Mini Ammo Chests aren't attracted by default, they are unaffected.
Rabbit Paw		Mini Ammo Chests and Mini Medkits drop from enemies 40% more often, in accordance with pickup drop rate rules.
Recycle Gland		Each bullet that hits an enemy or prop has a 60% chance of giving you  +1 bullet type ammo back. Heavy bullets and Ultra bullets give +2 ammo back, as they cost 2 ammo to fire. This mutation does not work with Pop Bullet Weapons, even though they use bullet type ammo.
Rhino Skin		Adds 4 max HP and heals your character for that 4 HP. You can also revive Chicken by choosing Rhino Skin while she's headless inside a portal.
Scarier Face		Enemies spawn with 20% less HP, rounded to the nearest whole number. This includes bosses. This doesn't affect destructible objects.
Second Stomach		Doubles the health received from HP Pickups, making them give 4 HP instead of 2 HP. Medkits give 8 HP instead of 4 HP. This also affects Robot, with eaten guns giving 4 HP instead of 2 HP. Bloodlust isn't affected by this mutation. The double multiplier is added before the Crown of Haste effect. With this crown, HP Pickups will heal for 5 HP instead of the regular 4 HP. Stationary Medkits are unaffected by the crown and will heal for 8 HP.
Sharp Teeth		Taking damage deals 2.5x the amount of HP you lost to all enemies currently on the screen. This is especially useful for self-damaging characters like Rebel and Skeleton or characters with plenty of HP like Crystal. Damage prevented by Boiling Veins, Strong Spirit, or taking more damage than your remaining HP will not count for the damage dealt to enemies. Unusually, this is one of the only ways that enemies can take decimal damage.
Shotgun Shoulders		Shell Weapons' projectiles bounce further and travel faster after hitting a wall. Normally, shell weapons deal more damage up close. With this mutation, their projectiles also deal that increased damage right after bouncing off of walls (for two frames after bouncing, check the weapons page for the increased damage values). While this mutation does work with Flame Pellets, they can only bounce once and not as far as normal Pellets. Also works on Pop and Flame Pop Bullet Weapons, although they use bullet type ammo.
Stress		Increases rate of fire in relation to the amount of currently missing health. The fire-rate buff provided by Stress is inversely proportional to the percentage remaining of max HP, giving up to 200% rate of fire (Normal 100% + Stress's extra 100% fire rate at 0 HP). You can calculate your reload speed with (1 + (1 - (HP / Max HP))) * 100 or 100% + (Missing Health%), so for example if you're at 4/8 HP (50% Missing Health), you would have 150% reload speed. Rhino Skin and Crystal (particularly with Fortress) work well with Stress, as having higher maximum HP will allow safer thresholds of HP to rest at for better reload speed. Having low HP, such as with Melting, is also a benefit, as less HP is needed to be lost for better reload speed. However, this would also cause a lower maximum use, as well as being harder to obtain without dying. Having Strong Spirit also synergizes well with this mutation, as it allows characters to more safely achieve their maximum effect for Stress in more scenarios. The only character that can reach 200% and not die is Chicken without her head. Even if you have 20 max health as Crystal, the highest reload speed you can have without dying is 195% on 1 HP.
Strong Spirit		When charged, Strong Spirit activates upon death and revives you with 1 HP. After activation, it cannot be activated again until it is "recharged". This can be accomplished by replenishing your health to its maximum value, but only once per level at most (i.e. once Strong Spirit has been recharged, it cannot be recharged again until you have gone through a level ending portal, even if it is activated again and you replenish your health to its maximum value again within the same level). If Strong Spirit is charged, a halo will appear above your character's head. Death is prevented for 5 frames (1/6 of a second) right after Strong Spirit has been activated. To be clear, you can still get hit during this time, but you cannot go below 1 HP. This is especially useful to protect you from things that ignore normal i-frames, like explosions and Gator shells. Having very high max health can be troublesome with Strong Spirit, as it means that more health must be collected to recharge the mutation after it's expended. However, since Strong Spirit can only be recharged once per level at most, it is still better to have high max HP than low max HP, as having low max HP will not allow Strong Spirit to prevent death more often. In particular, having exactly 1 max health (which is generally only possible if playing as Chicken or Melting) will limit Strong Spirit to save you from death only once; it can't be recharged at all afterwards unless more max HP is somehow obtained.
Throne Butt		Upgrades your character's special ability. Fish: Roll is replaced with Water Boost. Can be used for as long as the active button is held and can change directions while boosting. Crystal: Shortens shielding time and allows Crystal to teleport to the cursor's location after shielding for long enough. Eyes: Doubles Telekinesis' pull and push speeds. Melting: All corpses explode into 3 blood explosions, instead of just one. Plant: Snare kills enemies under 33% health. Y.V.: Upgrades Pop Pop into Brrrap, shooting your weapon 4 times with 3× reload time. Steroids: Firing one weapon has a chance to add a small amount of ammo for the other weapon. This is more likely to occur when both weapons are being fired at once. Robot: "Better weapon nutrition" gives 1 extra health/ammo pickup after eating a weapon. Chicken: Thrown weapons pierce through targets. Rebel: Gives allies a better weapon which increases their fire rate by 60%. Horror: Every second using Horror's beam heals 1 HP. The beam also gets wider twice as fast. Rogue: Makes Rogue's Portal Strike explosions much bigger. Skeleton: Adds a 1/3 chance that Skeleton won't take damage with Blood Gamble in addition to his regular odds. Frog: Causes all toxic gas to spread further and faster. Big Dog (playable character): Projectile and missile attacks move faster.
Trigger Fingers		Each enemy killed reduces your remaining reload time on both equipped weapons by 40%. This only affects the current reload; it is not a permanent reduction. Great for the Nuke Launcher, Heavy Crossbow, Plasma Cannon, or any other weapon with long reload time and high damage, as either killing enough enemies with it will quickly reload it or using another weapon to kill enemies will help reload it while it is stowed. Melee weapons are affected as expected, and as such the interval between swings is also greatly reduced with this mutation.

Ultra Mutations table

Going over level 9 and essentially reaching level 10 (Level Ultra) allows you to choose one of the character-specific Ultra Mutations. On the experience bar, the number 10 is replaced by a crown icon, indicating that your character has reached its full potential. This adds 1 extra mutation to the max that your character can have. That's a total of 9 mutations, 10 with Crown of Destiny, 11 if you also picked Patience, and 14 if you play as Melting with his second Ultra Mutation.

Character	Ultra Mutation	Icon	Description
Fish	Confiscate		Enemies have a 20% chance to drop an Ammo Chest (which can also be a Present Chest or an I.D.P.D. Chest) or a Medkit instead of regular mini pickups. They can also drop regular Weapon Chests instead of weapons. Not opening the Weapon Chests counts towards a Large Weapon Chest spawn. If you have a Crown, enemies can rarely drop a Cursed Chest.
	Gun Warrant		Weapons don't consume ammo for 7 seconds after exiting a level ending portal.
Crystal	Fortress		Adds 6 max HP. Crystal will instantly get healed for 6 HP. Can be stacked with Rhino Skin for a max of 20 HP.
	Juggernaut		Enables slowed movement while shielding.
Eyes	Projectile Style		While using Telekinesis, your projectiles will be frozen in a stationary position on top of Eyes, in the direction of where you shot your gun. Upon deactivating Telekinesis, all projectiles will continue to travel towards their initial destination and behave as normal. Melee weapons will have less range while using Telekinesis.
	Monster Style		Push away nearby enemies. Enemies will be pushed passively when not using Telekinesis.
Melting	Brain Capacity		Enemies at 5 HP or less will blow up along with corpses upon using your active ability. This includes undamaged enemies.
	Detachment		Lose half of your maximum HP to immediately get 3 more mutation choices.
Plant	Trapper		6 Snare Growth vines appear instead of 1, covering a much larger area.
	Killer		Each enemy killed while snared will spawn deadly Saplings, which fly around and will home towards other enemies, dealing 5 impact damage and afterwards causing 3 closely packed Blood Explosions. Each Sapling has 10 HP and can explode upon taking 10 or more damage. Each blood explosion deals 4-12 damage and destroys any projectiles in the blast radius. Blood explosions don't destroy walls and do no damage to the player.
Y.V. (Yung Venuz)	Ima Gun God		+100% higher rate of fire. With Y.V's passive, that makes 60% higher rate of fire for all weapons (weapons have 40% of their regular reload time). It also affects how fast a weapon reloads after using Y.V's active ability. After using Pop Pop, the weapon will have 80% of its regular reload time. With Throne Butt, that's 120%. Also sends you to Y.V's Crib.
	Back 2 Bizniz		Pop Pop will fire off 50% extra trigger pulls that won't consume ammo and won't affect the reload time. This means a total of 3 trigger pulls with a cost of 2 ammo and 160% of the weapon's regular reload time. With Throne Butt, Pop Pop will fire a total of 6 trigger pulls with a cost of 4 ammo and 240% reload time. Also sends you to Y.V's Crib.
Steroids	Ambidextrous		Regular Weapon Chests and Cursed Weapon Chests increase in size and drop two of the same weapons. Large Weapon Chests drop four random weapons instead of three.
	Get Loaded		Regular Ammo Chests increase in size and have 10 Mini Ammo Chests inside, giving two for each type (bullet, shell, bolt, explosive, and energy). Synergizes well with Crown of Love.
Robot	Refined Taste		Only higher tier weapons will drop from Weapon Chests and enemies. This means that Robot won't find weapons which normally (without Robot's passive) start dropping from chests in area 3-1 and below (check the Weapon Chest drops table). Any weapons left behind when leaving a level will be automatically eaten.
	Regurgitate		3/7 (~43%) chance to burp out a random stationary chest (Ammo Chest 50%, Weapon Chest ~33%, or Medkit ~17%) after eating a weapon. The chests will spawn on top of Robot and instantly open. Ammo Chests have a chance to spawn as I.D.P.D. Chests. Weapon Chests can spawn as Cursed Weapon Chests if you have a Crown. Any weapons left behind when leaving a level will be automatically eaten. If Robot regurgitates while automatically eating a gun, he will not also automatically open the regurgitated chest, leaving it behind.
Chicken	Harder to Kill		Each enemy killed by Chicken adds 1 second to the time she can survive while headless. The timer won't go above 5 seconds.
	Determination		Thrown weapons teleport to your secondary weapon slot after being thrown. Weapons thrown inside a portal are not affected.
Rebel	Personal Guard		Rebel starts each level with two allies. All allies will also have 30 HP instead of 12, which in addition lengthens their lifespan.
	Riot		Every time Rebel uses her active, she spawns two allies instead of one. Each spawn will cost 2 HP.
Horror	Stalker		Enemies that normally drop rads and Rad Canisters explode into radiation beam pellets upon death/when destroyed. The projectiles shoot out in all directions and otherwise act like parts of Horror's radiation beam, dealing 1 damage each. Exploding doesn't reduce the amount of rads they will drop. The amount of beam pellets each enemy/Rad Canister explodes into is 60% of the amount of rads it drops. That includes radiation added from other Horror's beam pellets hitting the enemy before it dies. Enemies that don't drop rads (like the I.D.P.D. or Small Green Rats) and Destructible Objects are not affected by this mutation, unless they are hit with Horror's beam pellets. I.D.P.D grenades are detonated if they collide with rad pellets, which can be dangerous when fighting I.D.P.D. Freaks at close range.
	Anomaly		Level ending portals appear slightly before you have killed all enemies in that level. The portal opens when their combined health is equal or below 140. All remaining enemies are killed in the process. Synergizes with Scarier Face and/or Crown of Luck.
	Meltdown		Doubles your Radiation capacity, increasing the amount of rads Horror can use for its active ability and Ultra Weapons.
Rogue	Super Portal Strike		Doubles Portal Strike ammo capacity. Portal Strike Ammo Canisters will give two ammo instead of one.
	Super Blast Armor		Upgrades Blast Armor. When Rogue gets hit, it creates four individual explosions in a triangular formation.

Character	Ultra Mutation	Icon	Description
Skeleton	Redemption		Turns Skeleton back into Melting. Every mutation you picked while playing as Skeleton will be removed. You'll be able to pick nine new ones (standard eight and one extra) and one of Melting's ultra mutations instead. Melting will have base 2 HP as opposed to Skeleton's 4 HP.
	Damnation		Firing a weapon with Blood Gamble will reduce that weapon's reload time by 80%. This only affects the current reload; it is not a permanent reduction.
Frog	Distance		Causes rads dropped by enemies and Radiation Canisters to emit toxic gas. Each Rad has a 1/3 chance to create one toxic gas cloud. Radiation Chunks are guaranteed to create 4 toxic clouds.
	Intimacy		Frog continuously spreads toxic gas as it moves. This also affects Frog's active ability, which, instead of charging a big cloud of gas, will release it as you hold down the button.
Big Dog (playable character)	Ultra Spin		Spin Attack fires double the amount of projectiles.
	Ultra Missiles		Missiles constantly fire projectiles. Each projectile deals 3 damage.

 

Co-op Ultra Mutations table

Going over level 9 when playing in Co-op and essentially reaching level 10 (Level Ultra) allows you to choose an Ultra Mutation unique to Co-op which will affect both characters. You will pick it instead of the character-specific Ultra Mutations listed above, which are unavailable in Co-op.

Mutation	Description
Blood Bond	Health pickups are shared. Picking up a Mini Medkit will restore 2 HP of both players simultaneously.
Gun Bond	Ammo pickups are shared. Picking up a Mini Ammo Chest/Cursed Mini Ammo Chest will give its full amount of ammo to both players simultaneously.