Break Mind

A spell to cause unimaginable amounts of pain to a person, leaving no physical mark and causing no physical harm. The affected entity must not be undead or mechanical. The target makes a Wisdom saving throw, equal to the Spell DC of the person casting the spell. On a successful save, the affected person cannot do anything for two rounds, and drops whatever object/weapon they are holding, as well as stopping any actions.

On a failed save, roll a D100:

• 0-5; the DM chooses one friend of the target and one enemy of the target. The target now cannot differentiate between the two.
• 6-10; the target remains in the material plane, but believes they have been transported to a random Plane of Existence.
• 11-15; the target loses use of one of its limbs/appendages, being unable to move or control it in any manner, for some time.
• 16-20; the target emits a constant screeching/wailing (unless physically/magically prevented from doing so) for some time.
• 21-25; the target believes they have been transformed into a small animal, such as a weasel or a cat, and must behave as such for some time.
• 26-30; the target is paralysed for some time.
• 31-35; the target loses all ability to articulate words until the end of a short rest. They can understand speech in their usual languages, and from telepathy. Any attempt at a response (either psychic or verbal) comes out as garbled sounds, meaning spells with a verbal/semantic component cannot be cast either.
• 36-40; the target is imbued with a keen and fervent belief in a god of the DM's choosing. Whether that faith persists is either down to dice roll, or DM discretion.
• 41-45; the target loses proficiency in one of their weapons, and it is replaced by a proficiency in another random weapon. Whether this change is permanent is down to dice roll or DM discretion.
• 46-50; the target becomes incapable of understanding anything communicated to it, either psychically, bibliographically or verbally, for some time. They are capable of perfect speech during this, although anything communicated to it has no meaning whatsoever to the affected person.
• 51-55; the target becomes incapable of lying for some time. They may opt to not tell the entire truth, although anything they DO say must be true.
• 56-60; the target is filled with violent urges, attacking anything it can with its bare hands for some time. It does not discriminate between friend and enemy, although it retains recognition of friends.
• 61-65; the target is filled with a deep innate fear of one specific animal or type of object. They must make Wisdom saving throws whenever around the animal or object, else they run in fear.
• 66-70; the target becomes a pathological liar, finding it just about impossible to tell the truth about something, no matter what the situation or how dire it may be.
• 71-75; the target becomes homicidal by nature, although retains their intellect (i.e. feels strong homicidal urges, but if they succeed on a Wisdom saving throw, they may choose not to murder). 
• 76-80; the target hallucinates vividly for some time. They may perceive people that are not there, weather effects that are not happening, or that they are in an entire alternate reality altogether - the DM may choose.
• 81-85; the target develops a deep and inexplicable obsession with one living, friendly entity that it can see. The obsession is only curable with a Greater Restoration spell, a Wish spell, or direct divine intervention.
• 86-90; the target is filled with deep self-destructive urges, They must randomly make Wisdom saving throws, and on a fail, they attempt to use whatever tools they have available to them to cause themselves harm. They may not kill themselves.
• 91-95; the target develops a pathological hatred of sunlight, and will do whatever they must to be in the shade. This may be as simple as walking with a cowl on, or it may be skulking through alleyways, but they must constantly have a hatred of being in direct sunlight, and suffer charisma and intelligence penalties (due to being distracted by their hatred) when in direct sunlight.
• 96-100;  the target develops a split personality. One is destructive, manipulative and evil, and will do whatever they can to derail their friends plans - the other is a truly good pacifist (even against known enemies) and will do everything in their power to see their friends succeed their goals. This is only curable by divine intervention, at which point the original personality of the character is restored (with the memories of both splits). The entity must roll a d6 each time they wake up. An odd result yields the evil personality, an even one yields the altruistic one.