Help with Horror

Okay. So basically, I want to add a little horror session into my non-horror campaign. My players are all big horror lovers and I want to make sure they can really feel uneasy and tense. Issue? I'm basically a first time DM and not sure what to do to unsettle my players. I've been looking into some tips for horror campaigns, but I'm not sure how to transition from the false-security bit into the real tension of it.

Basically, what I have so far is that in the middle of their boss fight (I have a rogue, paladin, and fighter at lv 3 btw) the boss' magic goes awry and they suddenly wake up on a day several weeks ago, before the campaign started. Just a normal day. All of the leads they were following are cut and all the NPCs they knew have normal, happy lives. It's as if they're insane for remembering anything else. They're gonna end up meeting up at some point, and the boss (Vince Sterling, they/them) shows up to, explaining that they don't know what he did and that they need to work together to get out of here. Vince Sterling is trustworthy and the only person other than the main fun gang that remembers anything differently. I have a premade description for if the paladin tries to use Divine Sense, which I'll include in the lil spoiler thing below. Please, any help would be GREATLY appreciated!

First thing to consider about running horror is that the most important element, by far, is atmosphere; that still applies with this less conventional horror scenario.  Based on your description of the scenario: you'll want to have this "happy vision that's actually rotten underneath" to at first seem perfectly idyllic; but also include subtle hints that things are "wrong".  Some good sources for examples of this done well: "Perchance to Dream" - Episode of Batman The Animated Series, "Turn Left" & "Forest of the Dead" Two episodes of Doctor Who that depict a "subtly wrong" world, "Hot Fuzz" is another good example from film, as is "The other world" from Coreline, the "Tranquillity Lane" quest from Fallout 3, post-death sequence in Fable II, and overall vibe of the town in We Happy Few also are good examples.  It's a tricky balance to strike: but you want to achieve "normal/idyllic with subtle undercurrent of "wrongness"."  Psychological horror is an inherently "slow burn" sort of affair; and tension is always better than shock or action.

The addition of a paladin is an interesting twist to things: since the paladin will be at an information "advantage" compared to the rogue and fighter.  Functionally: the paladin will be the ONLY one of the trio to "Know" that something is amiss at first.  You should probably lean into that; have the opportunity for the other two to "notice" something amiss; but it should be hidden behind skill-checks and observations to them; where-as the Paladin has the definitive answer.  Lean into the mystery; at first it should be reasonable for the other two to guess that they have simply time-traveled; but they can put the peices together if they care to dig further.  By that same token though; horror is very dependant upon the players' buy-in; you won't be able to scare or unnerve/unsettle them if they're cracking jokes and aren't present in the scene so to speak; so if your group is of the "wacky" persuasion you may have to crack down on that a bit.  Being "uncertain" is part of achieving the horror/unease feeling; and since your Paladin CAN be fairly certain if they have their ehad in the game; the other two will have to be the uncertain ones; you want them to question if the Paladin is just being paranoid and their cursory observations are to be trusted instead.

If you play on VTTs; audio can be a VERY powerful tool for building atmosphere; depending upon what you use for that, you can even layer or cross-fade tracks as your players dig deeper and unravel what is going on.  There's a whole science to why certain tones make us feel "at ease" or "on edge".

Body horror: either a monster thats a frankenstein aggregation of limbs and different creatures sewn together, OR have an enemy that magically starts to transform on of the players that fails a con save. They target a character (biting delves into horror), and by that players next turn, their hand has turned into a lobster claw or tentacle. They dont get a save on that turn, which will freak them out because they might think its unstoppable. Next turn, its up to their elbow. Then let them save. On a success, it stops, but remains a claw or tentacle.

After combat, a arcana check from your wizard determines that greater restoration will revert thr spell. If they do nothing, after an hour, it will be at their shoulder, and maybe it stops there, but they wont know that for another hour or two.

And this is important: the hand turning into a claw doesnt effect the player in any major way.  They can still use it to grapple, attack, use a wand, whatever. Its just going to freak them out.

Why? Because this isnt anywhere in the rules.  If you have a monster in the monster manual show up and do whatever it does in the manual, even turn their hand into a claw, odds are a lot of players will know what it does and how to fix it.

And then, leading up to the encounter, keep describing bits of information that will inform the players of impending horror. A corpse thats half human, half lobster. Weird runes on the floor. 

And then this is the important part: NEVER tell them meta information, during or after the game. Someone will want to know what it was, so they can normalize it, make it a known threat, understand, prepare.

Do NOT answet meta questions, especially about your homebrew horror stuff, because one thing that makes it work is it is an unknown quantity.

That's really helpful, thank you! I just got a couple questions. Should I split up the party at any point? I also kind of want to give everyone the responses to the checks seperately, so the other players only know the reaction of the person who did said check. Would that be a smart approach or could that end up being difficult?

That's really helpful, thank you! I just got a couple questions. Should I split up the party at any point? I also kind of want to give everyone the responses to the checks seperately, so the other players only know the reaction of the person who did said check. Would that be a smart approach or could that end up being difficult?

Quote from CaptainJinxed >>

That's really helpful, thank you! I just got a couple questions. Should I split up the party at any point? I also kind of want to give everyone the responses to the checks seperately, so the other players only know the reaction of the person who did said check. Would that be a smart approach or could that end up being difficult?

 I would say yes; both of those are good ideas if you think you have the skill to pull them off without disrupting the flow of play too significantly.  Giving the players different amounts of information and relying on them to share it means that they will have to be active participants in solving the mystery instead of you just giving the party the answer.  Most VTTs have a "whisper" mechanism for that sort of thing; if you're playing in person; pre-writing notes to hand out is a good substitute, or just having a second voice channel if you're using a voice-over-internet program like Discord.

Starting them off in different locatiosn will also help sell the illusion so to speak: IE: start them in the location their character would reasonably be at that point in time they believe they are waking up in.  Leave it up to the players to find one another; this can help sell the difference between them and the NPCs; that they remember something everyone else doesn't.  You want to make them feel isolated and vulnerable in a scenario that "should" feel normal so to speak.  Of course; this can be a bit challenging depending upon how you handle maps and visuals but it can be done.

Quote from CaptainJinxed >>

That's really helpful, thank you! I just got a couple questions. Should I split up the party at any point? I also kind of want to give everyone the responses to the checks seperately, so the other players only know the reaction of the person who did said check. Would that be a smart approach or could that end up being difficult?

Never split the party.  NEVER split the party.

The party may try to split, but strongly advise them not to.

The problem with splitting the party is that whoever is not actively playing will completely check out of the game. They will go to the fridge and graze. The moment someone does that, the other players will ask them to bring food. Everyone is distracted. People will start doing their taxes or working on a term paper that is due soon. They will lose interest in whatever horror thing you have going on, will come back 2 hiurs later and say "what did i miss?" And someone who was there will say "Bob had his hand turn into a lobster claw, but we fixed kt." And they will say "cool". 

As a dm, part of your job is cat herder. When the party goes shopping everyone wants to split up and shop at andifferent store. I find it better if you rotate from one player to the next every once in a while,.almost like initiative, so everyone is active.  During combat, when you tell the wizard its their turn, look at the initiative order and tell the druid "youre up next". Id the wizard cant decide what spell to cast, IMMEDIATELY go to the druid, resolve their turn, and then ask the wizard if theyre ready. The thought of losing initiative clarifies combat choices for most players.

As a dm, never ever ever split the party.

And if the party splits in a dungeon, one player will inevitably run into a monster designed for 5 players and get wrecked. At which point, the players will be deincentivized to split up. 

I have to fundamentally disagree with the "never split the party" rhetoric.  That's meta-advice for players; not an absolute rule for DMs.  The idea that because the spotlight isn't equally shared by everyone at all times is somehow ane xcuse for players to "wander off to the fridge" is a mark of disengaged players, not necessarily bad DM work.  Players that are engaged with the story and scenario SHOULD care about the state of their companions.  Some great moments in my games have arisen from one half of a split party desperately trying to reach and assist the other half.  Combat is one thing; then you have a disconnect between one set of players and another; but ina  story-heavy scenario; mingling at a party, infiltrating a hideout, shopping in town etc.; it's incredibly inorganic and immersion breaking to have a arbitrarily chain all your party together.  The party should WANT to stay together out of comradery and mutual assistance; not be forced to by DM mandate.  And when it IS required they split up, which will happen for reasons of party specialisation; the Paladin in plate mail is not going to be helping the Rogue sneak into a gate-house to open the door for them; then that's fine.  It's especially important for this scenario: to achieve a horror atmosphere, players need to FEEL (not necessarily "be" but that helps) vulnerable; and it's hard to feel vulnerable if you have several heavily armed guys ready to dog-pile anything that leaps out at you; part of why combat in survival horror games is actually aided by being "awkward" or "clunky"; it aids in the feeling of vulnerability; that your character isn't ready for anything.  Anyone who has played games like Lethal Company can tell you nthe moment one of the group gets inadvertantly seperated is when the tension ramps up.

Yes; it is true that part of a DM's job is to "herd the cats" as you said; but it is also part of the players' job to be mentally present.  Just because it isn't presently "their turn" isn't an invitation to be AFK or to start browsing Reddit.  That's the case in "Roleplay/Story time" and "Exploration/Investigation time" just as much as it is in "Combat time".

"It's especially important for this scenario: to achieve a horror atmosphere, players need to FEEL (not necessarily "be" but that helps) vulnerable; and it's hard to feel vulnerable if you have several heavily armed guys ready to dog-pile anything that leaps out at you;"

Any feelings players experience during combat can be the same feelings whether its 1v1 or 4v1: Players dont want their character to die. Combat could kill them. But thats not specifically horror.

I had a bunch of sessions where the players were dealing with a cult. They would find npcs who were clearly charmed, and quietly singing "ring around the rosey" in a slow, quiet, completely disconnected way, their eyes staring off into space. 

They find an expert on the cult who tells them that the lyrics to the song contain verbal components of a spell that summons the evil god they worship, who then takes your soul leaving an empty, soulless shell of a body.

All of that was set up for a session later where they ran into a cult spellcaster who would sacrifice people tontheir god. And during combat, i had a player make a wisdom save, they rolled a 4, and then i handed him a not that said "start singing ring around the rosie". They did. The room screamed. Everyone screamed.

Thats horror. Everyone was in the room. Having a party of "heavily armed" allies doesnt protect you against the things that horror does to you.  On everyones turn, each player changed fighting a room full of xultists to trying different things to try and save their friends soul. Everyone was terrified, cause they didnt know how to stop it and they didnt know if they could stop it. They had to break the concentration of the caster to stop the spell, and they had to get the player out of the rune circle to break the connection to the soul stealing god.

Eventually they figure it out, but for a number of turns, nobody knows whats happening pr how to stop it. Meanwhile the player stared off into space, quietly singing a nursery rhyme.

The key to horror, best as i can tell, is the unknown.  

Maybe their hand starts transforming into a lobster claw, something thats in no rule book, something that no player will know how to stop it, they wont even know IF they can stop it.  

And if the unknown is a slow transformation, like the hand transforms into a claw, then the wrist, then the elbow, creates a timer with an unknown deadline. Timers increase tension of almost any situation. A horror timer is usually a timer where the deadline is unknown.   How long does someone sing the song before a part of their soul is permanently stolen? Thats something you do NOT tell the players. Then when one of the players starts singing, everyone screams, cause no one knows how long they have before their player friend is dead.

The "cure" can be fairly easy, stop the spell and remove from rune circle, maybe break the gem that channels the god, but the players dont know that. After the player starts singing, the next player to go might try something to help, but because its a multisept process, it has no effect. All the steps must be complete to stop the player from singing and save their soul. But the players dont know that. They just know they tried one thing, and it didnt stop. Maybe they cant stop it. The panic continues.

THAT is horror.

And you didnt even do anything to the characters, damage wise. While singing, the player is charmed, singing, and cant move.  But takes no damage.  Whe. The players do the thing to break the ritual, the player stops singing and is unharmed.  While the hand turns into a lobster claw, they still have full functionality. And when they donanremove curse plus greater restoration, the hand looks like a hand and is all back to normal.

Its the unknown outcome, an unknown timer deadline, not knowing if you can stop anything, not knowing if you can fix anything. Thats horror