How to creatively use spells without cheating?

[Svelte Bird]

I am running a 5e mini campaign soon.

I am creating a combat where there will be a 1d10 chance of something happening if they fail their charisma save. They're fairy tale themed effects.

D1 Sleeping Beauty = Unconscious

D2 Red Riding Hood = Frightened

D3 Rapunzel = Restrained in golden hair

D4 Snow White = Poisoned

D5 Little Mermaid = Wall of water?

I was thinking for D5, using wall of water that immediately drops on the failed PC and maybe an additional dexteritysave to see if they hold their breath in time to not take in air (and thus the timeline of drowning is hastened).

Would this be alright, or is this a flagrant disregard of 5e? I want to be creative, but I don't want my players to feel like I'm out to get them (not my intent at all).

Also, I am open to suggestions for the other 5 (fairy tales and effects).

Any ideas and feedback is welcome.

[Psyren]

For D5 Little Mermaid I would go with Silenced, your theme seems to be curses/conditions that were inflicted on the princesses.

[JonBeowulf]

D6 Jack and the Beanstalk = Enlarge/Reduce spell
D7 Three Billy Goats Gruff = Troll appears, combat ensues
D8 ??
D9 Three Little Pigs = Wind Wall
D10 Hanzel & Gretel = Maze spell, but with a lower DC to escape

[Anymage]

Not cheating. Published material is basically stuff that some other writer made up, so you making your own stuff up is cool.

Having said that, being subject to repeated Cha saves means that someone's going to roll low eventually, so you don't want the conditions to be too strong. Unconscious is an outlier here, since it deprives the PC of a whole action as well as making them vulnerable. (And that's assuming the conditions only last for one round, otherwise there's the potential for more swinginess.) Little Mermaid's water effect can similarly be having the water dump knock the PC prone and maybe push them back. For Sleeping Beauty, Incapacitated with sleepiness for the round is as powerful as I'd expect the ability to go.

As for more slots, I'll point out that 7 is a classic fairy tale number. Either have six with the villain being the seventh, or roll a d8 and reroll the eights. Charmed by the villain might also be a useful effect, as would one round of Confusion (as per the spell), another incapacitate from another strong emotion (Hideous Laughter gave me this idea), or being compelled to spend all your movement either towards or away from the villain.

[Bohandas]

I agree that Little Mermaid shouls be Silence

[schm0]

The designers encourage you to use spell effects as trap effects, so there's no reason why they can't work here. As the DM, the sky is the limit. There's no cheating, only creating things that are unfair. So if the spells you are using for this magical effect are one's they might face from a CR-appropriate caster, then go for it.

I would recommend using the following spell replacements for each of your effects, depending on party level and obviously reflavored to fit your theme:

Sleeping Beauty = Sleep (upcasted if needed)
Red Riding Hood = Cause Fear/Fear/Phantasmal Killer
Rapunzel = Ensnaring Strike/Entangle/Evard's Black Tentacles
Snow White = Ray of Sickness/Dragon's Breath (Poison)/A poison of your choosing from a monster that deals poison damage
Little Mermaid = Wall of Water/Water Sphere... maybe a charm effect based on her voice?

You get the idea.

[Mastikator]

I agree with mermaid = silence.
Red riding hood should be attacked by a wolf that grapples and restrains when it bites, followed by devour whole on the next turn if still grappled and restrained (but no damage while inside the wolf)

Some other options for D6-10

Tiana = polymorphed into a frog
Belle = imprisoned by wall of stone
Cinderella = all your gear turns non-magical and non-functional temporarily
Mulan = a red dragon wyrmling shows up
Elsa = deal cold damage to allies unless using action to conceal and not feel

[LibraryOgre]

Silenced, and maybe Prone.

[Svelte Bird]

So if the spells you are using for this magical effect are one's they might face from a CR-appropriate caster, then go for it.

Oh for sure this is level appropriate effects. Thank you for this insight. :)

I love the point that 7 is a fairytale number, I think I will shorten the table down to 7 (and reroll the 8s)

Little mermaid being silence is a fantastic idea from multiple of you. I think I will change it to that.

I like the red riding hood one. That's a difficult one to combat, but appropriate as they will be level 10 in this mini campaign (3 sessions)

I love all of your suggestions Mastika.

Problem with sleep is they are level 10 and there's no good way to roll high enough to get even one person. To the point that that affect is basically useless.

I'm also thinking that instead of if they fail a charisma save, now that I'm thinking in spells and not just conditions, that I will go with the saves put in spells.

It's not just plain casting, this is a literal book worm monster that "casts" by thwapping them with their book tail.

So instead of a charisma save, I think I will make it a melee spell attack and it can choose to make a damage roll or cause the affect.

D1 Sleeping Beauty = Spindle appears and the PC must save as if charm person has been cast on them. Spindle appears 1d4 squares away. PC can make a save on each round or they will be released from the affect when they reach the spindle (1d4 damage from spindle if they touch it, but no sleep affect).

D2 Red Riding Hood = Phantasmal killer of a wolf over a loved one that they have killed and is now stalking the affected person. Lasts 1d4 rounds, can make a save each round.

D3 Rapunzel = Entangled in hair. Makes saves as if Entangled has been cast normally

D4 Snow White = Ray of sickness. Smells like an orchard of fresh apples and cinnamon.

D5Little Mermaid = Silence area affect lasts 1d4 rounds

D6 Jack and the beanstalk = Reduce
Bean stalk appears in front that is 20 feet tall. Once climbed the top of bean stalk, they will be returned to their normal size. Otherwise, the affect lasts 1d4 rounds

D7 Three little pigs = Gust of wind in a straight line towards the PC that was attacked. Lasts 1d4 rounds

Thank you all for helping me brain storm!

[Derges]

Just to point out unless your combat is going to go on for over 8 (or 7) rounds there is no difference from your players' perspective of a random order of conditions and a scripted one.
Consider if rotating through them with some indication of what might come next would be more fun for your players.

As a player, I hated it when my DM would randomise parts of his setting at the table because for me the other 99 outcomes never existed and never could because the event only happened once.

[Mastikator]

You don't need to match the sleep spell to cause sleep. For example a beholder has a sleep ray and it doesn't involve hit points at all, you simply fail the save and fall asleep (but otherwise works the same). You could steal the effect from the beholder.