Danganronpa 2: Goodbye Despair has Junko doing this to the entire cast of the game in the real world (the game primarily takes place inside a simulation of the character's lives before she did this.) She transforms them from generally decent and friendly high schoolers to self-mutilating sadists with no intentions in life except to cause as much pain and despair as possible. The Ultimate Despairs are barely seen onscreen, but what we do see and know about them is rather unnerving.
Chapter 6 Danganronpa V3: Killing Harmony has Tsmugi, Monokuma, and the entire audience verbally abusing Shuichi, Maki, and Himiko, after they reveal that the game is an actual reality show based off the now in-universeDanganronpafranchise, and currently in its 53rd season (or 50th, since it had to have started with Danganronpa 4 at the earliest). The cast (barring Keebo) were given fake memories to disguise this fact, and once they discover the truth, their reactions were so disturbing and traumatizing.
In Tsukihime, after the extremely violent awakening of Tohno SHIKI's (the real one) demon blood, he is "taken care of" by Synchronizer Kohaku. Meaning, in his insane state, he rapes her for the life energy that will help calm the demon blood. Kohaku responds by using drugs, lies, and turning him against his father to make him her puppet who has absolute zero chance of ever recovering from his insanity and demonic blood. In Hisui's True End, this all finishes with Kohaku manipulating SHIKI into killing his sister, and having the fake Tohno Shiki (he's adopted) finish off the heavily wounded, thoroughly broken, and completely insane SHIKI, ending the Tohno line completely.
The final battle goes from Takumi and Norose dueling to Norose using Noah II to assault his mind with images and delusions to try and break his will and shatter his mind. This ranges from him forcing Takumi to believe he's being impaled on a giant spike from underneath for 3 days straight as he sinks into it, to slicing him in half, to making him nearly rape Rimi who he's trying to save, and so on. Takumi manages to eventually turn this around on Norose by creating the delusion that his body isn't organic and can regenerate, which makes him basically invincible.
Route B of Chaos;Head takes this one step further, Suwa manages to mentally shatter Takumi by making him mentally endure the deaths of every one of the people that died in the New Gen incidents, and the brutality and horrifying pain of the deaths breaks him. Thankfully this is non canon.
In a similar fashion to Chaos;Head, Chaos;Child has the final battle focus on Takuru being forced to witness the death of his sister Nono repeatedly, and then he's dropped into an abyss where he can't feel or touch anything which slowly drives him insane over the course of what he feels to be a month. It takes him re-creating his imaginary friend Serika in his mind to shake him out of this, and he turns the delusion back around on Sakuma who inadvertently lets him free of the delusion as a result.
"Psychic" may not be the right term, but in Doki Doki Literature Club!Monika tampers with the other girls' character files so their worst personality traits are amplified, as a form of in-universe Flanderization. This leads to Sayori going from someone who uses a Genki Girl appearance as an attempt to cope with her depression to someone who is full-blown suicidal; Yuri, a Shrinking Violet with odd interests, developing into a Yandere prone to Self-Harm; and Natsuki, the game's resident Tsundere, becoming prone to full-on verbal abuse instead of just being defensive. Eventually, it leads to Sayori committing suicide at the end of Act 1, and Yuri doing the same in Act 2.
In Sable's Grimoire: Man and Elf, mind destruction magic is a forbidden type of magic which does exactly what its name implies. Sable is secretly studying it for theoretical purposes at the start of the game. He can use a mind destruction spell to kill the Big Bad, but doing so leads to a bad ending.
