A Power-Upgrading Deformation will make a character or creature much stronger but also make them look at the least inhuman and at the worst horrendous — and the process isn't likely to be pleasant or pretty either.
Unlike the Psycho Serum where an ugly appearance can be a side effect, for the Power Upgrading Deformation the newly ugly appearance is the source of the enhancement: like sprouting Combat Tentacles, pincers, supermassive muscles, My Brain Is Big, grotesque Cybernetics, etc. Because of this it would technically still be considered a Magic Enhancement or Super Serum and not Psycho Serum.
If the setting has a Bishonen Line, this drug, technology or spell will take the character to just before the return to prettiness (or if already there, start the cycle over). It's also worth noting that protagonists and main villains may get off easy with cool looking alterations that are way more powerful while Mooks and secondary characters aren't so lucky.
The deformation may be a mix of: permanent (requiring a cure to remove) or temporary (granting a Super Mode), and perfectly stable (no more mutations) or continuously changing (risking falling to The Corruption or Power Degeneration). Because its effects are so nasty taking it tends to be treated as a Godzilla Threshold, with only the direst of situations meriting it. Villains like the Mad Scientist and Evilutionary Biologist will delight in kidnapping victims to use this on… usually paired with a Mind-Control Device of course! note On the other hand, some villains may take it themselves, become a One-Winged Angel and proclaim A God Am I! Truly, Evil Makes You Monstrous. Mind the Clipped-Wing Angel from overdosing.
Compare Dangerous Forbidden Technique, Evolution Powerup, One-Winged Angel, Hulking Out, Cursed with Awesome and Transformation of the Possessed. See also Beauty to Beast and Deadly Upgrade. Pretty much all Lovecraftian Superpowers result in this.
- When Zondark is unable to defeat Guts, the Count makes him swallow a part of him. This not only makes Zondark physically more powerful, but gives him the ability to grow Combat Tentacles to replace lost limbs. The Count himself is one of the many Apostles, who have all been originally human. The Apostles can assume a human form but when they go One-Winged Angel "deformed" is an understatement.
- Guts receives a set of magic armor, the Berserker Armor, that ups his already amazing combat abilities to the point where he seems almost untouchable, and even Apostles have difficulty fighting him. However, he's been warned that using it for too long will result in him losing his humanity. He's already begun to feel the effects: there's a Skunk Stripe in his hair, and he's lost some of his sense of taste and colors are dulled in his vision. It's implied that the Skull Knight, an undead armored skeleton, was turned into what he is via many years of using the Berserker Armor.
- Bleach gives us Ichigo's Hollowfication, as well as the Vizoreds who have similar powers. By tapping into their inner Hollow, they gain immense strength and speed, but have a bone-like demonic looking mask grafted onto their faces in the process. It is only temporary though. The mask can be broken off in battle, and it'll eventually crumble away in time. The mask's appearance varies from person to person, but all of them stop looking human.
- In Claymore, this is how the titular Super Soldiers are made, grafting in a piece of demon flesh to give them some of its powers, but they eventually succumb to The Corruption, if they don't give in to their Superpowered Evil Side.
- The Zoanoids in Guyver are basically mutated humans whose new (revolting) forms are always tailored to give them a specific strength or super attack. Zoalords are however higher on the Bishonen Line and look far less ugly than their underlings.
- This seems to be at least partly design philosophy rather than anything inherent to the process. Later developments give us the relatively more huamn looking Bio-Freezer, Libertus and Griselda zoanoid forms.
- Zarbon in Dragon Ball Z has a powerful second form, but it makes him look fat and ugly (whereas his normal form is a Bishōnen), so as a matter of vanity he avoids using it.
- High School DXD has Issei after he sacrifices an arm to temporarily gain Balance Breaker. This sacrifice is not actually losing the arm, its that whenever the energy in the arm builds up too much it begins to look like a dragon's rather than human.
- Jagaaaaaan, the Fractured Humans gain lovecraftian superpowers from the Frenzied Frogs which has to merge with them in order to happen. The power-up comes with a disturbing,physical change that they can't control and makes them stand out like a sore thumb when among ordinary humans. That the change is permanent tends not to bother them, as they're far too out of their minds to care.
- The Tavoo/Taboo race in Psyren all have a core known as an Illuminus, which heightens their psionic abilities, but often disfigures them to the point of not even looking human anymore, usually taking on an insectoid appearance instead. The few exceptions are the high-ranking W.I.S.E. members, and several others such as Tatsuo and Alfred.
- Similar to Claymore example, if the Magical Girls of Puella Magi Madoka Magica falls into Despair Event Horizon, they will turn into Witches. This is actually a subversion, since Witches lose their sanity and acts purely on instinct, making them less effective in actual combat.
- In The New Universe in general and DP7 in particular, the White Event makes people suddenly have power-related mutations, many of which are like this. Moreso minor characters than the main ones, which for all their complaints are really not that bad.
- Marvel's The Incredible Hulk, Dr Banner transforms into a giant green rage monster and has mega strength.
- In the New 52 reboot of Animal Man, Buddy Baker now actually physically changes shape when he uses animal powers. The transformations are NOT pretty.
- The Fantastic Four's The Thing is perhaps one of Marvel Comics most iconic examples. After passing through a cloud of cosmic radiation he grew a super tough rock-like hide and Super Strength to match. The downside is that unlike Reed, Sue and Johnny he can't turn his powers on and off, and is always the same huge frightening rock monster; an issue which has caused him no end of grief and in some continuities even suicide attempts.
- The Ultimate Marvel Reed Richards, in his identity as The Maker, distorted his skull◊ into an odd shape to better reconfigure his neural structure. Similarly, Rhona Burchill, the Ultimate version of The Mad Thinker, has a deformed skull from transplanting extra brain matter from her brother into it.
- In Origins, a Mass Effect/Star Wars/Borderlands/Halo Massive Multiplayer Crossover, this is discussed by an ex-Cerberus Phantom. The cybernetics process turns skin blue, leaves hardware sticking out, blood tends to seep out and cake in places, etc. In exchange, her weak biotics are massively enhanced (the Systems Alliance believed making such minimal talents military-grade to be excessively risky). Implied to apply to all Cerberus troops to some extent, as her engineer friend is just as ugly as she is.
- In Pirates of the Caribbean, Davy Jones and his crew are immortal, but have spent so long neglecting their job of Psychopomp for the dead at sea that they've become half-morphed into sea creatures. On the plus side, they're now fully amphibious. It's not clear if their ability to walk through walls/teleport from ship to ship is part of their curse, but it's a great plus either way.
- In the live-action Street Fighter movie, the project behind creating Blanka is basically an attempt at creating mutant Super Soldiers and brainwashing them.
- In A Macabre Myth of a Moth-Man, both the titular Moth-man and Ozzy were horrifically mutated (they both used to be normal guys), but also became much more powerful as a result.
- In The Elric Saga, human soldiers pledging alliegence to Chaos gradually turn into monstrosities who are part-man, part animal. This makes them harder fighters but at the expense of human intellect and intelligence. Michael Moorcock returns to this theme in the Hawkmoon books, where the élite legions of GranBretan are human in form but wear realistic beast-masks according to their animal totem. And behave accordingly. Here, the degradation is more symbolic and internalised. And just as terrible.
- Just about every Chaos mutation in Warhammer and Warhammer 40,000, since these mutations include things like Combat Tentacles, pincers, extra mouths, cancerous growths...
- In 40K, most augmetics (metal replacement parts, ranging from bionic eyes to replacement arms to Doctor Octopus-style dendrites) are rather crude and ugly (ork versions are even worse). The Adeptus Mechanicus see the replacement of flesh with metal as the ultimate way to better themselves, so naturally they get the worst reactions from normal humans.
- Even becoming a Space Marine, the de facto "heroes" of the 40K universe, involves some pretty gruesome procedures, like the addition of extra organs, genetic modifications that lead to superhuman size and musculature, metallic/ceramic replacements for your skeleton, and an implanted "second skin" that interfaces with your Powered Armor. Worse still, many of these upgrades are based on non-renewable implants that have to be harvested from dead Space Marines so they can be passed on to new recruits!
- Infernals in Exalted have access to the Malfeas charms "By Rage Recast" and "Devil-Tyrant Avatar Shintai". When the Infernal's anima banner flares, Rage Recast means they manifest a selection of mutations from a library it grants them - because after the first couple of rounds you really want the guy running on radiation and crazy to gain an extra two feet of height and sprout batlike wings. The Shintai is even more extreme, manifesting the entire library at once - which, at high Essence, can provide a great many fangs, tentacles and horns.
- For a Lighter and Softer version, the Child of the Sun in Chuubo's Marvelous Wish-Granting Engine can gain skills and minor powers by sprouting additional tendril-limbs. These powers tend to be based on the hopes and dreams of other player characters.
- In Vampire: The Masquerade, a Gangrel's animal features can be this, depending on the Storyteller. For example, permanent claws might be practical for a variety of reasons, but big ones don't exactly look that great on humans. Antlers could also be used as a defense, but try hiding those.
- Bio-Borgs in Rifts. Through the rather horrible magical art known as Bio-Wizardry, the Splugorth can transform mortal beings with a number of magical augmentations to turn them into living weapons. They get their name because they're basically an organic version of a mechanically enhanced cyborg. Most of them are of the Body Horror variety, though a lot of them can be hidden with some effort, and some are completely internal. But since this augmentation is normally performed on slaves, the Splugorth don't really care what the result looks like, and the slave doesn't get any say in the matter.
- In the fifth story line of BIONICLE, the Toa Metru are captured and injected with Hordika venom, which turns them into half-animals. Downplayed in that while greatly increasing their physical strength, it also degrades their elemental abilities to some extent. The real downside however is they can't use any masks of power.
- The basis for Splicers in the first two BioShock games. Specifically, they were users of a gene-modifying substance called ADAM- and along with the many cosmetic uses that it can be applied to, specially-prepared batches can give the user superpowers in the form of plasmids; unfortunately, abuse of the substance has resulted in addiction, disfiguration, and insanity. The main characters can also suffer a few of the tamer side-effects when they have plasmids equipped: Incinerate! clearly burns the wielder's hand; Winter Blast causes icicles to grow through the user's flesh (complete with blood); finally, Insect Swarm results in a mixture of nasty-looking stings across the hand (in Jack's case) or a honeycomb forming out of the palm (in Delta's case).
- Bioshock Infinite has Vigors, later revealed to be derived from early Plasmids. Vigors are drinkable plasmids that give the user powers similar to the first two games and generally serve the same roles with Possession/Hypnotize, Murder of Crows/Insect Swarm, Shock Jockey/Elecro Bolt, etc. Other Tonics introduce new attacks that serve as support in combat like Bucking Bronco,note Return to Sender,note and Undertow.note All of these warp Booker's hands to match their abilities and they were going to cause people to turn into Vigor Junkies, people who turned into Splicers from excessive ingestion of Vigors but instead of tumorous growths they gained massive crystals growing out of their bones and skin. Characters such as the Zealots of the Lady and Cornelius Slate,note while early artwork was integrated as Frosty Splicers, who overdosed on the "Old Man Winter" Plasmid.
- This comes up in Deus Ex; some cyborgs dislike the protagonist because they had to sacrifice their ability to look normal (thanks to the fairly obvious nature of their implants) while the protagonist's nanomachine based augments have barely any cosmetic effects (not to mention rendered them obsolete).
- Bydo-derived Organic Technology from R-Type, under certain circumstances. For example, if the Claw Force is detached from the fighter too long, it temporarily mutates and goes on a rampage.
- In Digital Devil Saga, everyone infected by the demon virus has access to demon form, which is stronger than human form. Said demon form ranges from looking vaguely humanoid (most of the main characters), to slimes, to animalistic, to the worst looking of Shin Megami Tensei demons.
- In the main Shin Megami Tensei series, human-demon fusion is quite likely to leave you like this, in IV, some of the poor bastards who chose to become Demonoids were hit with Fusion Errors. If you're not careful with Reds, in the same game, you will end up as a shambling undead. Or worse. Technically speaking, the Demi-Fiend is also an example, as the parasite warped his body into that of a demon, even if he still closely resembles his human form, the horn he got was noted by Word of God to be a primitive sensory organ that grants him much of his demonic power, and the Power Tattoos are actually lines of demonic lymph coursing through his body.
- Dr. N. Brio's appearances in the Crash Bandicoot series usually involve him drinking mutagen and turning into a hulking green monster (though by the time of Crash: Mind Over Mutant, it seems like he needs the mutagen to keep from transforming). At the end of Mind Over Mutant, Dr. Cortex samples the mutagen himself, with similar results.
- The Binding of Isaac has this as the de jour - nearly half the permanent items upgrade Isaac at the cost of visually maiming him. For example, a coat hangar goes straight through Isaac's eye socket to increase the firing rate of his tears.
- In Borderlands 2, one of Krieg's ultimate abilities is "Release the Beast", in which if he activates his action skill when at 1/3 of his health he transforms into a Badass Psycho: His torso and right arm grow in size while his left arm shrivels up into a tiny stump. During this state his melee damage and damage resistance is massively increased.
- Resident Evil runs on this. The boss will inevitably be a normal human who becomes a grotesque abomination mere minutes before gameplay starts. Often happens more than once per game, even.
- Downplayed in Pokémon, where The Power of Friendship allows some fully-evolved Pokémon to undergo a further transformation called "Mega Evolution". Unlike regular Evolution, Mega Evolution usually results in a Pokémon that's still recognisable as its original species, but with parts of its body becoming bulky and overgrown (and occasionally a Shapeshifter Mashup of previous forms). This reflects the nature of the process as a temporary Super Mode rather than a normal stage in their lifecycle.
- A number of human enemies from the Monster Girl Quest series experiment on themselves (or on others) to gain the same attacking capabilities as monsters, by infusing their bodies with monster DNA to sprout Combat Tentacles.
- Mutating in Cataclysm carries this as a downside. Each mutation has a visibility and ugliness rating, and visibly mutated players may have a harder time talking with other survivors.
- Veran of The Legend Of Zelda: Oracle of Ages has three One-Winged Angel forms beyond her true form as an evil fairy, but as they are rather grotesque — being giant insects with her face — she's loath to use them until backed into a corner.
- Fate/stay night: Rider has one ability that she never uses throughout the series: "Monstrous Strength". If she used it, she could amplify her already superhuman strength multiple times over, which would naturally be very helpful in battle. However, if she used that ability, it would also transform her into a hideous, monstrous form, implied permanently. Rider is shown to prefer death to actually using this ability, given what happened to her in her past life regarding her looks (her real name? Medusa).
- In Qem-95's project, Qem's Life Problems: Episode 1 - Tanning, Qem gains the ability to blend in with his parrot red towel due to staying in the tanning machine for too long AND forgetting to put on his tanning lotion.
- Kaijudo has The Choten's evolution drug, which transforms the series' normally one-form Mons into a new, stronger form.
- Street Sharks has the gene splicing treatment that turns humans into sharks (and sea animals into monsters).
- Every Teenage Mutant Ninja Turtles cartoon had the mutagenic ooze which made them more human-like, while also mutating humans into uglier mutants. Quite notable ones include Baxter Stockman (who was transformed into a fly-man) and the 2012 incarnation of the Super Shredder, which discarded the usual "giant Shredder with larger spikes" for "mutated humanoid that almost looks like Doomsday".
- The splicers in Batman Beyond used genetic engineering to become Half Human Hybrids, which generally while animalistic weren't ugly. When their boss fights Terry, he doses himself with a bunch of different serums and goes One-Winged Angel, becoming a huge, powerful, agile creature that retains his human intelligence. Terry manages to defeat him by giving him more doses of random drugs, pushing him into Clipped-Wing Angel territory, as he becomes more dangerous but also less stable.
- The reason that steroids are so dangerous is the litany of side effects that comes with abusing them. Yes, steroids increase your muscles and your strength, but it comes with very bad acne, allergic reactions, discolored skin and infections. It also essentially makes you a Clipped-Wing Angel version of yourself, weakening the bones, ligaments and tendons in your body, which makes debilitating injury much more likely.