These terrifying potions would be kept in secret for fear of someone stealing them or damaging them, loosing their terrible power unto the world at the wrong moment. These potions would cost 5150 gold to purchase, or half as much to sell.
Antipathy/Sympathy salve- (1 hour to perform this action. 60 foot range. Ingredients; The black heart of a demon, an elephant's musk gland, ambergris, a holy relic. Lasts 10 days) This potion attracts or repels creatures of your choice. You pour our concoction on something within range, either a Huge or smaller object or creature or an area that is no larger than a 200-foot cube. Then specify a kind of intelligent creature, such as red dragons, goblins, or vampires. You invest the target with an aura that either attracts or repels the specified creatures for the duration. Choose antipathy or sympathy as the aura’s effect.
Antipathy: The salve causes creatures of the kind you designated to feel an intense urge to leave the area and avoid the target. When such a creature can see the target or comes within 60 feet of it, the creature must succeed on a Wisdom saving throw or become frightened. The creature remains frightened while it can see the target or is within 60 feet of it. While frightened by the target, the creature must use its movement to move to the nearest safe spot from which it can’t see the target. If the creature moves more than 60 feet from the target and can’t see it, the creature is no longer frightened, but the creature becomes frightened again if it regains sight of the target or moves within 60 feet of it.
Sympathy: The salve causes the specified creatures to feel an intense urge to approach the target while within 60 feet of it or able to see it. When such a creature can see the target or comes within 60 feet of it, the creature must succeed on a Wisdom saving throw or use its movement on each of its turns to enter the area or move within reach of the target. When the creature has done so, it can’t willingly move away from the target. If the target damages or otherwise harms an affected creature, the affected creature can make a Wisdom saving throw to end the effect, as described below.
Ending the Effect: If an affected creature ends its turn while not within 60 feet of the target or able to see it, the creature makes a Wisdom saving throw. On a successful save, the creature is no longer affected by the target and recognizes the feeling of repugnance or attraction as magical. In addition, a creature affected by the spell is allowed another Wisdom saving throw every 24 hours while the spell persists. A creature that successfully saves against this effect is immune to it for 1 minute, after which time it can be affected again. (Potion)
De-evolution potion: (1 action. Consumed. Ingredients; A rat tail, pigeon feather, spider leg, wolf tooth, dragon scale, fairy blood. Lasts 24 hours) Your potion turns others into beasts. You can brew enough to change up to 10 people. You transform each target into the form of a Large or smaller beast with a challenge rating of 4 or lower. On subsequent turns, you can use your action to transform affected creatures into new forms. The transformation lasts for the duration for each target, or until the target drops to 0 hit points or dies. You can choose a different form for each target. A target’s game statistics are replaced by the statistics of the chosen beast, though the target retains its alignment and Intelligence, Wisdom and Charisma scores. The target assumes the hit points of its new form, and when it reverts to its normal form, it returns to the number of hit points it had before it transformed. If it reverts as a result of dropping to 0 hit points, any excess damage carries over to its normal form. As long as the excess damage doesn't reduce the creature’s normal form to 0 hit points, it isn't knocked unconscious. The creature is limited in the actions it can perform by the nature of its new form, and it can’t speak or cast spells. The target’s gear melds into the new form. The target can’t activate, wield, or otherwise benefit from any of its equipment. (Mutagen)
Deep Mind- (1 action. Consumed. Contains Tendril of a Mind flayer. Lasts 24 hours) The concoction alters the shape of the drinker's brain morphing it in unthinkable ways. Until the concoction's ends, one willing creature is immune to psychic damage, any effect that would sense its emotions or read its thoughts, divination spells, and the charmed condition. The concoction even foils wish spells and spells or effects of similar power used to affect the target’s mind or to gain information about the target. (Mutagen)
Immolation Miasma- (1 action. Thrown/Fired. contains Ifrit beard hair, soot and lamp oil. Lasts up to 1 minute) A swirling cloud of smoke shot through with white-hot embers appears in a 20-foot-radius sphere centered on a point within range. The cloud spreads around corners and is heavily obscured. It lasts for the duration or until a wind of moderate or greater speed (at least 10 miles per hour) disperses it. When the cloud appears, each creature in it must make a Dexterity saving throw. A creature takes 10d8 fire damage on a failed save, or half as much damage on a successful one. A creature must also make this saving throw when it enters the spell’s area for the first time on a turn or ends its turn there. The cloud moves 10 feet directly away from you in a direction that you choose at the start of each of your turns. (Bomb)
Null globe- (1 action. Thrown/ Fired. Contains a pinch of powdered iron or iron filings. Lasts 1 hour) A 10-foot-radius invisible sphere of antimagic surrounds a point within range. This area is divorced from the magical energy that suffuses the multiverse. Within the sphere, spells can’t be cast, summoned creatures disappear, and even magic items become mundane. Spells and other magical effects, except those created by an artifact or a deity, are suppressed in the sphere and can’t protrude into it. A slot expended to cast a suppressed spell is consumed. While an effect is suppressed, it doesn’t function, but the time it spends suppressed counts against its duration.
Targeted Effects. Spells and other magical effects, such as magic missile and charm person, that target a creature or an object in the sphere have no effect on that target.
Areas o f Magic. The area of another spell or magical effect, such as fireball, can’t extend into the sphere. If the sphere overlaps an area of magic, the part of the area that is covered by the sphere is suppressed. For example, the flames created by a wall o f fire are suppressed within the sphere, creating a gap in the wall if the overlap is large enough.
Spells. Any active spell or other magical effect on a creature or an object in the sphere is suppressed while the creature or object is in it.
Magic Items. The properties and powers of magic items are suppressed in the sphere. For example, a + 1 longsword in the sphere functions as a nonmagical longsword. A magic weapon’s properties and powers are suppressed if it is used against a target in the sphere or wielded by an attacker in the sphere. If a magic weapon or a piece of magic ammunition fully leaves the sphere (for example, if you fire a magic arrow or throw a magic spear at a target outside the sphere), the magic of the item ceases to be suppressed as soon as it exits.
Magical Travel. Teleportation and planar travel fail to work in the sphere, whether the sphere is the destination or the departure point for such magical travel. A portal to another location, world, or plane of existence, as well as an opening to an extradimensional space such as that created by the rope trick spell, temporarily closes while in the sphere.
Creatures and Objects. A creature or object summoned or created by magic temporarily winks out of existence in the sphere. Such a creature instantly reappears once the space the creature occupied is no longer within the sphere.
Dispel Magic. Spells and magical effects such as dispel magic have no effect on the sphere. Likewise, the spheres created by different antimagic field spells don’t nullify each other. (Potion)
Vampire's bane - (1 action. Fired/Thrown. fire and a piece of sunstone) Brilliant sunlight flashes in a 60-foot radius centered on a point you choose within range. Each creature in that light must make a Constitution saving throw. On a failed save, a creature takes 12d6 radiant damage and is blinded for 1 minute. On a successful save, it takes half as much damage and isn’t blinded by this spell. Undead and oozes have disadvantage on this saving throw. A creature blinded by this spell makes another Constitution saving throw at the end of each of its turns. On a successful save, it is no longer blinded. This concoction dispels any darkness in its area that was created by a spell. (Bomb)
Vial of un-thinking- (1 Action. Thrown/Fired. Contains a handful of clay, crystal, glass, or mineral spheres) You launch a rich purple globe of gas which de-evolves the recipient's brain size, attempting to shatter its intellect and personality. The target takes 4d6 psychic damage and must make an Intelligence saving throw. On a failed save, the creature's Intelligence and Charisma scores become 1. The creature can't cast spells, activate magic items, understand language, communicate in any intelligible way. The creature can, however, identify friends, follow them, and even protect them. At the end of every 30 days, the creature can repeat its saving throw against this spell, If it succeeds on it's saving throw the spell ends. This concoction can also be ended by Greater Restoration, heal, or wish. (Mutagen)