Mutations are brand new additions added by the Colossus Update (Part 1). Mutations are powerful modifications that change the gameplay in some way. They typically come with a special ability with buffs and at least one negative. A player can choose up to 5 mutations to play with in one run. Experienced Disfigurers will switch out their mutations depending on what build they want to try next. A player can obtain all 5 mutations in one run, however to obtain just one mutation a player will need to defeat a boss. It is possible to skip a mutation selection after collecting it, however after defeating all 5 bosses, you will be unable to obtain all 5 mutations during the run, so it is wise to only skip if the option will seriously impact your run.

Mutations are very hit or miss. I've found that some downsides are too vicious for some modifications while others are too weak for the benefits. For those who just want a good list of mutations to choose from now rather than later, my go to is on the right and I believe has some of the best mutations available in Part 1.

Each Mutation has a number correlating to its position on the table. I haven't added the table here, but you'll see it easy peesy. Lets get started with number 13.

Number 13: Burger King- Bad joke didn't laugh. Number 13 is called SPROUT. It buffs Player movement speed by 30%, Enemy movement speed by 20%, and most importantly, buffs Enemy spawn rate by 20%.
This doesn't sound so grand, it sounds really dangerous actually, and it is. But the benefits far far far outweigh the costs in the long run. A Player obtains exp from defeated enemies, so what happens when there are more enemies to kill? Simple. More exp, which means more levels faster, which means more upgrades, which means becoming stronger quicker.
Sprout is top of the list because it always remains in my equipped mutations and is one of the first mutations I pick. However there is a couple of mutations that take priority.

Number 9: A Number 6 with extra dip. Also a bad joke. Number 6 is called REFINE. Every minute that passes after obtaining this mutation will increase fire-rate by 3%. I feel like this one is too under-powered compared to the next mutation I'll be discussing, but is still super strong because of the implications. REFINE is a buff that scales over time which in every game that has similar, is absurdly strong.
Lets do some math. Bosses 1-4 appear every 5 minutes. The final boss appears in 10 minutes. Overall to complete the game with all 5 bosses defeated, one will have to play for 30 minutes total. Take into account that the first boss appears 5 minutes from the start of the game. If you defeat the boss within the minute, that leaves REFINE 25 minutes of 3% increased fire-rate per minute. That is a 75% increase in fire-rate if obtained first. I last typically to 40 odd minutes after endless, this'll bump its total to a 105% increase if picked first. Its strong, but not as strong as this next one.

Number 4: I have no joke for this number ;-; Number 4 is called ROBUST. Every minute that passes after obtaining this mutation will increase bullet damage by 10%. Now this one is overpowered. Lets skip right to the math.
Bosses 1-4 appear every 5 minutes. The final boss appears in 10 minutes. Overall to complete the game with all 5 bosses defeated, one will have to play for 30 minutes total. Take into account that the first boss appears 5 minutes from the start of the game. If you defeat the boss within the minute, that leaves ROBUST 25 minutes of 10% increased bullet damage per minute. That is a 250% increase in bullet damage if obtained first. I last typically to 40 odd minutes after endless, this'll bump its total to a 350% increase if picked first. It is just as strong as it sounds and is a must pick for nearly every build in the game. If you believe your build will scale with bullet damage, pick this one first over any other mutation, even with REFINE.

Number 2: I don't really like to associate with this mutation. Its a bit of a LOOSE CANNON. As the name suggests, LOOSE CANNON is ye ol favourite Glass Cannon mode. 150% increased bullet damage, bested only by ROBUST obtained at the start of the game, this increase of damage to enemies also comes with an increase of damage dealt to the Player them self. Instead of hits taking 1 heart of damage, hits with LOOSE CANNON activated deal 2 hearts of damage. This cost can be countered with a shield, as any damage will simply break the shield like normal without a heart cost. But do try not to take any further damage. At nightmare, base health can survive 2 hits, and the Player must collect two extra hearts to survive a third hit. It is always risky, but always worth the outcome.

Number 7: Was in peace... Until the Burn nation attacked. Number 7 is called ELEMENTAL. Bullet damage is nerfed by 75%, but non-bullet damage is increased by 80%. This mutation confuses me. I'm not sure if the bullet damage nerf is considered in the calculations for the upgrades that provide the Player with non-bullet damage, if those upgrades scale with bullet damage. If it does, then this mutation will only buff non-bullet damage by 5%... I'm hoping the nerf and the buff are applied once the elemental type damage is dealt to an enemy.
Either way, you'd be surprised how good elemental damage is in Disfigure, most of, if not all of the powerful attacks are actually non-bullet damage types. Most of my most ridiculous builds have been ones unrelated to firing my gun for anything other than nuking a nearby enemy with a 300% elemental shot. Why wouldn't I want to buff those attacks? Even if the buff is a measly 5%.

I hate to be biased, but I find it unnecesary to go for any other mutations. I've swapped repeatedly for each build I did, but eventually I found that I stopped switching after equipping this setup of mutations. My equipped mutation loadout is based on high risk, high reward. Everything comes at you at mach 10 and you take double damage, but at least you get super scaling damage. Despite my bias, there are other nice builds, but I won't go too deep into them (Because they aren't as good :>).

Works best in easy, you noob.
BEHEMOTH for 20% increased damage per heart.
TANK for another 2 hearts.
AGILITY for yet another heart, if your noob ass hasn't already taken a heart of damage.
ROBUST 10% damage increase every minute baebae~.
LOOSE CANNON for another 150% increase in damage.
OR
SPROUT for that mob increase.
Don't get hit, pick up all 5 hearts to increase your health by 5. Enable ROBUST first, SPROUT second (if you have it at all), BEHEMOTH third, then choose whatever you want except AGILITY because that -10% exp gain nerf is atrocious. Only get it at the final boss.
This build should do an absurd amount of damage and also get you stuck in one spot forever. Pair it with handcannon and pile on damage buffs to race for the most possible damage one can do in a single shot.

This one could be pretty fun for a Concealed Fatigue build.
SHROUD is basically pocked Fatigue.
CRACK SHOTS pairs well with Concealed Fatigue's Shrouded Spiral for the bullet hell motif. Plus -25% vision.
That's it. Choose whatever else you want as long as it doesn't increase your vision size.

This one is atrocious. Don't do this one.
VISION BATTERY is a solid pick, actually lets you see so much.
COLOSSAL is complete garbage. This is actually never worth it. In fact, you'll probably find out if it is possible to get more than one boss on screen at once!
Thats it. DO NOT choose anything else to get the most out of COLOSSAL. You know you want that 30% movement speed and 15% vision size. All for the low low cost of 150% increased boss health! Would be 200% if you don't pick VISION BATTERY!!!

Well disciple, let me tell you.

1. The worst one by far is COLOSSAL. It is actually arse. Never pick this one up unless you like to suffer.
   
2. AGILITY is a close second. No matter what it puts on the table, that -10% exp gain is repulsive.
   
3. Lastly, CRACK SHOTS is weird. That -25% vision size is debilitating, just for a 25% chance to fire a bullet randomly. Its just weird.