Cursed Wish

A ritual mockery of the most powerful mortal magic, a cursed wish emulates the power and potential of a wish spell, but twisted in some way. A creature may be targeted by such a wish up to three times, and not more than once per day. After this, any subsequent wishes automatically fail. 

Price. Wishes made using this magic always contain a price or trick, or else come with a risk of inheriting a curse. Curses cannot be removed by any means short of a true wish spell. The DM determines the exact nature of such a price, and may feel free to get creative when doing so, though the price should never be worth more than the wish. If no obvious backfire, twist, or price is available, the speaker, or the target of a beneficial effect of the spell, suffers the effects of the bane spell for 1d4 minutes, or of a similar spell of 3rd level or lower of the DMs choosing.

Limits. While the speaker of the spell may feasibly wish for anything, there are limitations on the spell's power. For example, the spell may be used to replicate a spell of 7th level or lower from the Warlock's spell list, including a spell from any subclass of warlock, but cannot do so for any spell outside of this list. The spell cannot create magical, or even very rare objects. It may be used to summon or locate certain creatures, or even to create hazards and curses, but cannot create life or directly take it away, nor can it change a creature's personality or emotions beyond what is possible through a Warlock spell.

Hand of Cursed Wishes. The severed hand of a humanoid creature, or a humanoid-adjacent beast, may be used to create a focus for cursed wishes. If the speaker casts the spell without specifying a wish, and while holding such an article, the spell is instead stored within the object, and may be used while holding the object without additional material components, and with a casting time of one action. The hand may hold as many wishes as it has fingers. When a wish is used, one of the hand's fingers disintegrates into ash and is destroyed. The hand is immune to all non-magical damage so long as it contains at least one wish, and it does not decay, instead appearing to desiccate and mummify. 

If the spell is cast upon the hand every day for at least 44 days, the hand becomes a magical object in its own right. A Hand of Cursed Wishes my be used to cast as many wishes as it has fingers each lunar month. When a wish is used, one finger slowly curls inward to represent the use, even if the wish fails. The palm opens back up at midnight on the full moon, and all expended wishes are restored.

If the Hand of Cursed Wishes enters a field of anti-magic, it is immediately ravished by the effects of time, disintegrating at a rate of one finger per round, finishing with the palm.

Example wishes:

"I wish for [name an object]." The speaker ends the wish by naming a non-magical object with a gold piece value of 5,000gp or less, or simply wishes for the treasure itself. Material objects created by the use of this spell, such as food, treasure, or armour always looks perfect, but contains some hidden flaw. A banquet of summoned food is secretly riddled with maggots, and any treasure decays within a day.

"I wish to cast [name a Warlock Spell]." The speaker names a spell of 7th level or lower from the Warlock's spell list, or from a Warlock Subclass's expanded spell list, and may specify a target of the spell where necessary. The spell takes immediate effect without the need for additional material components, but may be twisted in some small way, and the details of the spell beyond the intended target are determined by the DM. Where creatively possible, these twists should make up the price of the spell. For example, an invisibility spell might not include a target creature's equipment and clothing. Meanwhile, a protection from evil and good spell may cause the target to gain disadvantage on attack rolls against the very creatures from which it is protected. 

"I wish for [name an ability]." The speaker ends the wish by specifying an ability, such as Strength or Charisma. The target of the wish gains a permanent +2 to the specified ability score. The speaker then rolls a d6 and a d4. The d6 decides a random ability score, where 1 = Strength, 2 = Dexterity and so forth. This ability is permanently reduced by an amount equal to the amount shown on the d4 - 1, even if the ability score is the same as chosen by the speaker.

"I wish to be skilled at [name a skill]." The speaker ends the wish by specifying a skill. The target of the wish gains expertise in that chosen skill. However, the target gains a permanent curse. Any time the target makes a skill check with a skill with a skill in which they are proficient but not an expert, there is a 25% chance that the check automatically fails, and is considered a critical failure.

"I wish for protection from [name a damage type]." The speaker ends the wish by naming a type of damage, such as fire, bludgeoning, or even necrotic. The target of the spell is permanently granted resistance to that damage type. However, the target gains a permanent curse. Any time they suffer damage of the chosen type, they become vulnerable to all other types of damage until the start of their next turn. They cannot become vulnerable to a damage type for which they have immunity. 

"I wish to find [name a place or target object]." The speaker ends the spell by naming something to be found, such as an object, creature, or specific place. The target must be something with which the speaker is at least vaguely familiar. If the speaker has never met the person they are looking for, they must at least know their name and have seen a picture of them. A small or tiny guide appears within 30 feet of the speaker. The guide is either a fey, a fiend, or some other form of extradimensional being, but may appear in the form of a mundane beast. The guide knows the location of the target, and is magically bound to lead the speaker to it in such a way that would feasibly take a day or less, but actively tries to place obstacles and dangers in the speakers way. The nature of such obstacles varies on the creature. For instance, a fairy dragon guide may choose a route that spans a raging river with no bridge, and simply fly across the river where it waits out the end of its service, leaving the speaker stranded on the other side, while an imp may lead the speaker to stumble upon a monster's lair. The guide vanishes upon reaching the destination, or after 24 hours, which ever is first.

"I wish to summon [name a creature]." The speaker ends the spell by either using a creature's true name, or simply naming a generic type of creature, such as a rabbit, a beast, a goblin, or a witch (hag). The spell magically teleports the closest example of such a creature to an unoccupied space within 30 feet of the speaker. If such a creature is not within 1 mile, the spell instead summons the closest approximation it can find. If the speaker invokes a true name, this range is extended to 10 miles. The spell cannot summon a creature from a different plane. One of the additional effects, chosen at random from the list below (roll a d6), or a similarly amusing effect of the DMs choosing takes place immediately after the wish takes effect:

1. The creature has advantage on attack rolls made against the speaker.
2. The creature is warded against the speaker who cannot directly target the summoned creature with any effect that requires an attack roll or saving throw, excluding saving throws made to avoid an area of effect.
3. The summoned creature is magically invisible for 1d4 minutes, and cannot be made visible by any means short of a 3rd level spell.
4. An aspect of the environment the summoned creature was in prior to being teleported comes with them. For example, if the summoned creature was in water, up to a 60 foot sphere of that water is teleported along with it. If it was in dim light or darkness before it was teleported, those shadows are teleported along with the creature, becoming a sphere of magical darkness with a 60 foot diameter centred on the target creature. Alternatively, furniture, plant life, or a collection of mundane objects come along for the ride. This effect cannot teleport additional creatures, nor any single object heavier than 50 lbs.
5. The target creature is not teleported at all. Instead, the speaker is teleported to an unoccupied space within 30 feet of the target creature.
6. The speaker and the target creature are both teleported, instantly swapping places for 1d4 minutes, after which, they revert to their original locations.