Brian,
Re curses, your observation that the RAW curses are short-term and only suitable for combat, whereas many legends about witches put curses in a much more foreboding context, has led me to these proposed revisions:
1- Change your more powerful curses to Ritual only, representing the extra work the witch puts in to cast a longer-lasting spell at a much greater range. The RAW Bestow Curse would remain as is, and the ritual version would be renamed Greater Bestow Curse.
2- Bump Greater Bestow Curse to 4th level, and Bestow Major Curse to 6th level.
3- Using RAW about ritual versions of spells, change the casting time to 10 minutes.
4- Change the range to Witch level x Slot level x 1 mile.
5- From the Contact Spirit of the Dead spell, use an adapted version of the strain test and the Relationship and Connection requirements.
6- Add these pre-requisites: Cauldron, link(s) with target.
Below are the proposed changes:
Greater Bestow Curse
4th-level necromancy (ritual only)
Pre-requisites: Cauldron, possibly link(s) with target
Casting Time: 10 minutes
Range: Witch level x spell-slot level x 1 mile
Components: V, S, possible M (see Connection in the spell description)
Duration: Permanent until removed
You magically reach out to attack a specific creature within range. You must know at least the name of the creature you are trying to attack. Cursing a creature can strain, or even injure you physically. When you cast this spell, make a DC 20 Constitution saving throw, modified as below.
Relationship (at most one modifier applies) Save Modifier:
Someone present whose testimony you trust adequately describes the target and its alleged wrong-doing: +2
You witnessed the target commit the wrong-doing: +4
You have successfully cursed the target before +6
Connection (at most one modifier applies) Save Modifier:
Likeness or picture +2
Possession or garment +4
Signature/prized possession or body part, lock of hair, etc. +6
On a failure, you take 4d8 necromantic damage and are stunned until you finish a long rest. While stunned, you can’t take actions, can’t move, can speak only falteringly, automatically fail Strength and Dexterity saving throws, and attack rolls against you have advantage. A greater restoration spell cast on you ends this effect.
On a successful save, one creature of your choice within range must succeed on a Wisdom saving throw. If the target fails, then beginning on the next dawn and continuing until the curse is removed, the target is subject to one of the following effects (chosen by you at the time the spell is cast):
• Choose one ability score. The target has disadvantage on ability checks and saving throws made with that ability score.
• The target has disadvantage on attack rolls against you.
• The target must make a Wisdom saving throw at the start of each of its turns. If it fails, it wastes its action that turn doing nothing.
• Your attacks and spells deal an extra 1d8 necrotic damage to the target.
• The target cannot regain hit points by any means other than natural healing, and natural healing recovers only half as many hit points as it otherwise would.
• The target falls in love with the next gender-and-species appropriate person it sees.
An effect of similar power that is appropriate for the target and approved by the DM.
At the time the spell is cast, the caster must announce an appropriate condition that will allow the curse to be broken. In addition, a remove curse spell ends this effect as described in the remove curse spell, but this spell cannot be dispelled.
At Higher Levels. If you cast this spell using a spell slot of 5th level or higher, there is no difference in the effect, but it will become more difficult to remove.
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Bestow Major Curse
6th-level necromancy (ritual)
Pre-requisites: Cauldron, link with target
Casting Time: 10 minutes
Range: 60 feet
Components: V, S
Duration: Permanent until removed
You magically reach out to attack a specific creature within range. You must know at least the name of the creature you are trying to attack. Cursing a creature can strain, or even injure you physically. When you cast this spell, make a DC 20 Constitution saving throw, modified as below.
Relationship (at most one modifier applies) Save Modifier:
Someone present whose testimony you trust adequately describes the target and its alleged wrong-doing: +2
You witnessed the target commit the wrong-doing: +4
You have successfully cursed the target before +6
Connection (at most one modifier applies) Save Modifier:
Likeness or picture +2
Possession or garment +4
Signature/prized possession or body part, lock of hair, etc. +6
On a failure, you take 4d8 necromantic damage and are stunned until you finish a long rest. While stunned, you can’t take actions, can’t move, can speak only falteringly, automatically fail Strength and Dexterity saving throws, and attack rolls against you have advantage. A greater restoration spell cast on you ends this effect.
On a successful save, one creature of your choice within range must succeed on a Wisdom saving throw. If the target fails, then beginning at the time described below, the target is subject to one of the following effects which must be appropriate to the target (chosen by you at the time the spell is cast):
• One minute after the spell is cast, the target is polymorphed into a beast whose challenge rating is equal to or less than the target’s (or the target’s level, if it doesn't have a challenge rating). The target’s game statistics are as described in the polymorph spell.
• The next time the target falls asleep, either naturally or by magical means, it cannot be awoken until the curse is ended.
• The target is struck by wanderlust. Beginning the next dawn, it begins to travel to see the wonders of the world. The wanderlust lasts for one decade.
• The target immediately is subject to constant, embarrassing faux pas. This effect lasts until a beautiful person agrees to marry the target.
• Beginning at the next full moon, the target is transformed into a lycanthrope. This lasts until the target sincerely repents for his past murders.
• Starting with the next dawn and lasting until the target solves a riddle posed by the caster, the target has disadvantage on all ability checks, attack rolls and saving throws while in direct sunlight.
• One hundred and one days after the spell is cast, the target must succeed on a new Constitution saving throw. If it fails, then it immediately drops to 0 hit points and begins dying. This curse cannot be broken but it is suspended for as long as the target sincerely foreswears earthly power and possessions, and lives a simple life.
An effect of similar power that is appropriate for the target and approved by the DM.
This spell cannot be dispelled, but a remove curse spell ends this effect as described in the remove curse spell.
At Higher Levels. If you cast this spell using a spell slot of 7th level or higher, there is no difference in the effect, but it will become more difficult to remove.