So, Magical Girls. I'm gonna write a bunch of different types, because the genre has lots of subgenres and someone made a joke about playing a campaign of all-mahou shoujo. So challenge accepted. For the record, if these all exist in one setting, they're not called, in universe, by their different types. Puella Magi don't call themselves such; Magical Girls tend to call themselves such, and differentiate by team names.
There's a lovely Madoka Magica-inspired game called Magical Burst about cute Magical Girls suffering dark fates, and I find it conceptually interesting enough to adapt it into its own spinoff variant. Mechanically, I'm going to call them Magical Bursters.
A Magical Burster is just like a Puella Magi in all respects, except they don't have Soul Gems, Telepathy, nor can they regrow their body from nothing, due to their soul not being in an external item. That said, a Magical Burster that would be 'killed' while in Henshin state effectively ignores any damage, instead returning to mundane form and losing their ability to transform and do magic for 24 hours.
Additionally, there's the matter of the Wish. They don't get one. We need to go a bit into lore for a second.
Kyubey isn't the only one recruiting Magical Girls (assuming these co-exist in the same setting); there are also the Tsukaima. They can look like anything, but are generally some kind of obnoxiously cute and colorful magical creature. They claim to be made of positive emotions and magic, as the antithesis of the Youma.
They do not offer a wish at the outset (their spell lists should thus be defined around a concept or the Magical Burster's personality; think elemental/conceptual affinities), but their deal is perhaps sweeter. A Magical Burster otherwise has no use for Grief Seeds, but if they give a Tsukaima thirteen of them, they can grant you a wish. You're not limited to doing this once, though you can't use a Grief Seed for this purpose once it's been used to cleanse a Puella Magi, so there's some tension.
In addition, a Magical Burster does not collect Corruption, but Overcharge (using all the same methods), and their Overcharge has no limit; they can collect as much as they want. Pretty cool deal!
Hahahaha yea go ahead and cast all the spells you want, you fucking idiot.
Magical girls shed Overcharge through Fallout. Fallout is the unwanted side-effects of using magic and fighting Youma. Such side-effects can warp reality, affect a magical girl’s behavior, induce magical mutations, and in extreme cases unleash raw destructive power. These things catch inexperienced magical girls off guard, leaving them wondering where a strange impulse to break something or hug someone came from, wondering what’s going on around them, or wondering what’s happening to their bodies. Those who last long enough will learn that this is because of their magic, that it is part of the price they pay for the power they’ve gained. They aren’t aware of Overcharge as “points,” but they do feel a growing sense of unease, and quickly learn to be careful.
Fallout can be deliberately induced once a day, and can otherwise be released involuntarily at the GM's discretion. Additionally, if a Magical Burster has 10+ Overcharge, it is automatically released after the end of the most recent combat, when they make camp/take a rest, die, or have an emotional meltdown.
Magical Burst as a game system tracked three or four different kinds of Overcharge in different meters, but honestly fuck the shit out of that. I'm using one pool and you can just roll randomly, or have the context of the most recent point gained color the nature of the Fallout. I also added a couple more types to bring things up to a d6.
Magical girls always suffer the highest type of fallout for the amount of Overcharge they have on a given attribute, and cannot lessen the effect of it by taking multiple instances of less powerful fallout. If you have 6 Overcharge, you will take a Temporary Change, and cannot take a Major Distortion and a Minor Distortion instead. If a magical girl has only 1 Overcharge, the player can ask for a Minor Distortion to remove the single point if they want.
Minor Distortions represent low-level twists based on the 'color' of the Overcharge and the Magical Burster's specific magical affinity. The six types of Overcharge are Magic, Heart, Fury, Madness, Despair, and Hope.
If a Minor Distortion is Magical, then the environment is warped in some plausibly deniable, but still strange way. The weather changes very abruptly, all the cats in the area converge in one spot, objects keep falling in unlikely ways, birds’ magnetic sense is thrown off in the area, etc. The kind if shit that gets people suspecting witches in their communities even if everybody's on the level.
Heart distortions result in the stress of what you’ve experienced causing you latch onto people around you in a way that’s a bit unsettling. A minor Heart distortion results in a moderate display of intimacy to someone, such as a lingering hug, blurting out personal stuff about yourself, abruptly inviting someone on a date, etc.
Fury distortions result in sudden, violent outbursts that you can’t really explain. A minor Fury distortion results in doing some property damage or having a minor violent outburst against someone. I know most players are murderhobos so make this meaningfully disruptive like mouthing off to the king or something.
Madness distortions result in temporary bouts of insanity. Amnesia for an hour or switching your personality and identity for a day or something, or even just being in shock. Basically, the Confusion spell.
Despair distortions are similat to the above three, but in a self-destructive, depressed way. Destroying things you care about, or making casual suicide scares like self-harming.
Hope distortions are your lucky break. Any other minor distortions are cancelled, a little bit of luck goes your way, your mood improves, and you probably get some bullshit platitude that gives a hint towards something like a puzzle solution or some bullshit.
Major Distortions, as the name suggests, is a more severe version of the Minor Distortion fallout effect.
A major Magic distortion causes something impossible to happen, but something that people can dismiss as imagined. Falling objects can hover or change direction, a door doesn’t quite deliver you to the right place, unnatural weather, an animal starts walking through walls, a person flickers in an out of existence for a little while, etc. This should be tied into the Magical Burster's affinity if at all possible.
A major Heart distortion results in a more extreme display of intimacy to someone, such as kissing someone out of nowhere... and stalking them obsessively for like a week. Usually culminates in a major invasion of privacy
A major Fury distortion results in a major violent outburst that could legitimately hurt someone. Usually culminates in a serious assault.
A major Madness distortion results in a permanent insanity. Multiple personalities, ongoing amnesia, major, persistent delusions and hallucinations, crippling phobias, etc.
A major Despair distortion results in a Magical Burster incidentally or deliberately trying to cut off their social ties and isolate themselves, and can often culminate in a significant crippling of self-sabotage of their major goals or a serious suicide attempt.
Major Hope distortions are the bottom of Pandora's Box. This ends all temporary mental penalties on a person, invigorates them with a temporary Hit Die until the end of the next combat, and gives them 5e-style Advantage on their next Saving Throw. Also, they're just really cheery for a bit.
Temporary Changes are mutations that last an hour or two to a full day, as dramatically appropriate/interesting. Again, stylized to their Overcharge type.
Magical changes should be blatantly supernatural, as opposed to body horror. Things like your elemental affinity/spell list changing every day randomly, or having technicolor anime hair or neko kitty ears, spawning a non-Magical Girl clone of your self that wants to take over your life, an Evil Eye, being immune to gravity to such an extent that you can't safely be outdoors without flinging into the sky, things like that. Basically, it's maximum Wild Magic.
Heart changes generally make you a stupid moe archetype waifu character. You look like someone you have a crush on, you can't touch anything like a ghost, you turn into a cute, Tsukaima-like creature except when you Henshin, you become the opposite sex, you get a single, useless angel wing on the side, a high pitched anime voice that breaks into random cutesy noises or untranslated Japanese, things like that.
Fury changes are corruptions from the mind of a 14 year old edgelord who's trying too hard. An aura that makes animals hate you, hulk outs, a constant hunger, your clothes turning into spiked rocker leathers, your eyes crying blood, a loss of ability to sleep, light sources going out in your presence, poltergeist activity... you're basically slowly turning into a japanese horror movie villain.
Madness changes are where you bust out your typical lovecraftian body horror mutation tables. You have one, right?
Despair changes have some overlap with Fury and Madness, but generally the theme is sadness. Necrosis, becoming a vector for horrible diseases, an unholy aura that makes you treated as undead to your detriment, typical vampire weaknesses, an anti-Charm Person aura that makes people refuse to be your friend, etcetera.
Hope changes tend to turn you into your idealized form. Ability score buffs, new abilities with no downsides, or the removal of negative changes tends to go here. You want to roll this result.
Permanent Changes are just like Temporary Changes, but last forever.
Bursts are the moneyshot of this mechanic. The fuck you, everything goes to shit button every GM wants to smash like a new lover in the sack.
Magical Bursts are the excess magical power you’ve accumulated turned into an explosion of raw power that annihilates anything and anyone nearby, excepting beings of considerable magical power. The blast covers 1dX x 1000 yards, where X = The Overcharge points, and everything caught in the blast takes Xd20 damage. Unattended non-magical objects, as well as anyone brought to -10 HP (or 0 HP or whenever people die in your game), is disintegrated. Saving throws are not permitted, though spellcasters and similar are able to expend Spell Slots to shield themselves, on a 1:1 basis. For example, a 5th level spell slot sacrificed will absorb 5 points of Overcharge in regards to the spellcaster specifically; protecting someone else means expending even more spell slots to shield them magically. If the Magical Burster has no relationships or positive ties to the world (such as if she accidentally just killed everyone she loves), she turns into an Youma from despair and regret.
Heartspawn are the intense magical power within you, although derived from warm human emotions, becoming dangerously twisted, and breaking off into a new being. This spawns a Shadow, a Youma with HD equal to the Overcharge vented into it. It is formed from your feelings towards the person you love the most, and will attempt to find and kill them. The Youma does not drop a Grief Seed until it has succeeded in killing this person. If you do not have any meaningful (as in more heartfelt than 'dead parents' and 'these guys I kill orcs with') positive relationships when you get this kind of Fallout, your loneliness combined with the excessive magical power will turn you into a Youma, made of hate and resentment at the world and those who abandoned you.
Berserker Rage is the Burst-level manifestation of Fury, which causes the magical girl to become consumed by rage. She glows a baleful red, and lashes out indiscriminately with a deadly strength, attempting to kill as many people as possible. Every action must be homicidal in nature if possible, and they always aim for overkill. They do not separate friend and foe, and will not be satisfied as long as anyone is alive. The Magus Child gains Rage Points equal to the Overcharge that went into the Burst, and the Berserker Rage lasts until she expends her Rage Points or is knocked out. If they're killed in this state, they become a Youma.
She can take two turns per round, rolling two initiative rolls. She gains 1d6 HP at the start of each turn she takes. She cannot gain Overcharge during this Rage. Each time she attacks, she must spend a Rage Point to do one of the following:
Spend 1 Rage Point to auto-confirm an attack (though this isn't treated as a crit, she still rolls to confirm one).
Spend 2 Rage Points to add +1d6 damage to a successful attack.
Spend 2 Rage Points to make an extra attack immediately after being attacked.
Spend 1 Rage Point to immediately move next to a target of her choosing.
She can also spend Rage Points as if they were Overcharge to cast spells.
Mad, Mad World is the Burst-level manifestation of Madness. The Magical Burster generates an insanity as usual, but gains an aura with a range equal to 1dX x 100 yards, where X equals the Overcharge points vented into the Burst. Within the aura, the Magical Burster's insanity has factual basis due to her magic. The thing she's paranoid about really are out to get her; she doesn't remember things because they don't historically exist for things in the field's influence; when she switches multiple personalities she literally, physically becomes that person. Think the Marauders from Mage: The Ascension. If the person's delusions convince them they're a Youma now, well...
Depths of Entropy is the Burst-level manifestation of Despair. The Overcharge vested into it become Sorrow Points, and as long as the Magical Burster has them, they are unable to benefit from any positive morale-based effects due to a depressive episode. Your Sorrow Points increase your capacity for critical failure/fumbling on a 1:1 basis, so if you have 10 Sorrow Points, you critfail on an 11 or lower. For every fumble you make in this state, you gain a Sorrow Point. For every success, you lose the difference between the maximum range and what you rolled. For instance, if your failure range was an 11 and you rolled a 14, you would lose 3 Sorrow Points. If you gain 19 Sorrow Points, you are incapable of avoiding critical failure, and completely give up on life as you curse the world, becoming a Youma. Additionally, you can still collect Overcharge during this Burst, unlike with Berserker Rage.
Hope Springs Eternal is the Burst-level manifestation of, well, Hope. When you have this Burst effect, you exchange your Overcharge for Optimism Points, which you must use immediately in the scene. Any Despair-based effects are automatically ended, and the Magical Burster can choose to undo one other negative effect of Fallout, such as another Burst or a Permanent Change. Note this generally only refers to ongoing magical effects, though a Magical Girl can choose to forfeit all her Optimism Points for a bullshit miracle like a World Healing Wave that fixes the blown up city and revives all the dead civilians like a wish on the Dragon Balls or the power of Love in a typical Magical Girl show. Failing that, a Magical Burster can exchange her Optimism Points to cast any spells, on any spell list, equal to their spell level. This means a Hope Burst can generally always afford a single 9th level spell at minimum, or just shove a shitload of little effects into a table-turning explosion of idealism.