Instakill Traps, and making them fair.

[Catullus64]

If a trap has an effect which may instantly kill a player (no damage involved, just death) how many chances should they probably get to avoid it? The standard setup is that you get one roll to notice the trap, and one roll to save against it, but dying immediately because you flubbed two rolls does seem a bit extreme. Take the following example from a game of mine, and modify it to seem more fair, as an example of how you think these things should work. DCs intentionally left blank so as to make it non level-specific.

The Golden Path
This sentient golden gate is charged only to open upon the performance of a sacred religious ritual, with difficult instructions scribed on it. Performing the ritual accurately requires a DC X religion check, or a DC X+2 Arcana Check. If the person conducting the ritual fails this check by 6 or more, the gate considers him a harmless buffoon, and merely refuses to open, raising the Religion and Arcana DCs by one. If someone fails the check by 5 or less, the gate recognizes an imposter of dangerous ability, and opens, but simultaneously opens a portal behind it into an pit of lava, disguised behind a Major Image spell of a nondescript hallway. Someone who fails to notice the illusion and walks into the hallway falls many stories into the lava and dies.

[strangebloke]

Instakill traps are only good with specific types of tables.

Highly lethal dungeon crawl with medium-to-high level characters where everyone rolled up a backup character? One ability check and one save is fine.

Game with a bunch of level 1 characters played by 12-year-olds? Low level narrative-focused game with backstories and special miniatures and commisioned portraits? Forget about it.

Somewhere in between? ...Somewhere in between.

In general, traps are lame. Use complex traps as outlined in Xanathar's and combo them with a regular encounter. Acid gas trap? Boring. Golem? Boring. Golem fight inside an acid gas trap? NOW you're talking.

[Avonar]

See that is the prime example of a bad trap. If you want am instant death trap, don't make it purely dependant on dice rolls or else players just feel screwed. No one likes losing a character to luck.

[Catullus64]

See that is the prime example of a bad trap. If you want am instant death trap, don't make it purely dependant on dice rolls or else players just feel screwed. No one likes losing a character to luck.

All death is ultimately down to dice rolls. Surely there exists something like an average minimum number of dice rolls which people will accept as a legitimate cause of death?

Without instant death as a factor, people would generally accept death in four rolls (one attack roll or one save, plus three death saving throws) as legitimate, albeit really lousy luck if you fail all four of those.

[Avonar]

All death is ultimately down to dice rolls. Surely there exists something like an average minimum number of dice rolls which people will accept as a legitimate cause of death?

Yeah but this is a case of fail by 1 and here's an instant death for you. If you don't pass the illusion ch3ck (if you make one, is there any reason to?) You die. That just sounds annoying.

[Lombra]

... this is still two flubbed rolls away from death?

Instakill should be obvious and clear. The player needs to know this, the description has to be clearly life-threatening, and should involve player skill over lucky rolls.

It is never fun to lose a character instantly, so make it clear that the trap IS deadly. Plenty of hints of previous failings should lay around or before the threat itself, and the context shouldn't leave room to interpretation, the player needs to know that his character is done if this goes poorly.

[DMThac0]

It's really dependent on the players' level and how long the adventure has been going on as to whether modifying this is necessary.

If, for example, the party is an average level of 4 and they've only played for a couple months, they may not have enough information and the gate would seem like an unfair act.

If, however, the party is an average level of 10, and they've been playing for 6 month, they should have a better idea that there are dangers like this. The gate would still be an upset if someone died, but it would be easier to handle.

--

In either situation, there are really only 3 options I can think of:

1) Alter DCs, or add a saving throw/clue, something to give the players an advantage.
2) Make sure the players are aware that death is a real risk, and handle it if/when a player dies
3) Find some way to bring the player back even though they are dead.

[Catullus64]

... this is still two flubbed rolls away from death?


I deliberately put the trap in an unfair, two-rolls-and-you-die format, to see what suggestions, dice-based or no, people had for improving its fairness.

Which you have begun to do in the rest of your post. Thank You.

[Trask]

I think a instant death trap isnt a cheap trick, and can make sense in the right environment (and at the right table as Strangebloke said) but whenever I do such a thing I always make sure that the threat can be telegraphed in some way. I wouldnt put an instadeath poison dart in a place where I have no real way of seeing it unless I made my investigation check. I'd make sure that there were bodies, and if they were inspected it would show traces of lethal poison, etc etc.

Or you can create a scenario where the "trap" is extremely obvious but there is a clear reward. Like putting a pedestal upon which rests a shining golden sword, but its surrounded in thick bubbling acid. Fall in the acid? Get dissolved. The player could see this by dropping stuff (even bodies) in there and make sure to describe how near instantaneously the body dissolves. They will get the message. Then they have to think of a create way to get to the sword. This is just one example but the principle is that a "trap" with instadeath properties doesnt necessarily have to be a "trap" at all, and in fact I think they work better as environmental hazards that the players can see but they just cant do anything about.

You'd be surprised how many players would risk it all for such a prize, and usually I find that theyre not upset if they die. They knew the risk and they took it. Knowing the risks, and taking the risks because the rewards are awesome, thats one of the best ways save or die can work, because everyone is on the same page about it.

For the specific purpose of your ritual trap, I think its a good idea and I like how the magic is not always playing nice. But I might include some tidbit about that. Someone knowledgeable enough to perform the ritual might know that such magical gates can be crafted in such a way that they obliterate intruders and robbers, and are not always compliant with the user who is not their master or creator.

You dont have to say anything about illusions or lava.

[Resileaf]

I think the best way to make an insta-kill trap like that would be to include a way to learn that there is a possibility of the trap doing this. A well-done research allowing the players to deduce what might happen from failure, and how they can prepare for it.

[Unoriginal]

OP, I have one question: do you consider spells like Disintegrate or Power Word Kill fair?

[MaxWilson]

If a trap has an effect which may instantly kill a player (no damage involved, just death) how many chances should they probably get to avoid it? The standard setup is that you get one roll to notice the trap, and one roll to save against it, but dying immediately because you flubbed two rolls does seem a bit extreme. Take the following example from a game of mine, and modify it to seem more fair, as an example of how you think these things should work. DCs intentionally left blank so as to make it non level-specific.

The Golden Path
This sentient golden gate is charged only to open upon the performance of a sacred religious ritual, with difficult instructions scribed on it. Performing the ritual accurately requires a DC X religion check, or a DC X+2 Arcana Check. If the person conducting the ritual fails this check by 6 or more, the gate considers him a harmless buffoon, and merely refuses to open, raising the Religion and Arcana DCs by one. If someone fails the check by 5 or less, the gate recognizes an imposter of dangerous ability, and opens, but simultaneously opens a portal behind it into an pit of lava, disguised behind a Major Image spell of a nondescript hallway. Someone who fails to notice the illusion and walks into the hallway falls many stories into the lava and dies.

It depends very much on playstyle. Let's ignore for now any potential debate over whether Major Image can produce an image of a hallway (because it could definitely produce an image of a floor), and whether or not the PC would detect the hot updraft from the lava. Handwave those away, and one might still argue that if this is the end of the PC, what really killed this player was being insufficiently paranoid: he didn't bring his 10' pole to test the ground, didn't test the archway with an orc/zombie/familiar before going through himself, didn't have Death Ward up to buy time to overcome the lava damage and/or Teleport out, didn't set up a Clone spell to retrieve him from death, didn't even have Feather Fall prepared.

If you pop them with enough traps like this, players absolutely can catch on and start doing the things that would have saved them from this trap. So the real question here is: do you want a game where being that paranoid is a thing? Do you want players to decline any and all obvious risks (like jumping in a hole whose bottom they can't see) because it's potentially suicide? Is an old-school murderous dungeon crawl the game you're trying to run?

If you have a game, like many people's games around here, which is about the PCs being Big Time Heroes and murdering hordes of monsters 6-8 times a day, and then you pop them with one trap out of the blue which kills a PC permanently ("You just jumped in a Sphere of Annihilation! Not one of the lame 5E DMG ones either--this one disintegrates you permanently if you touch it"), you're liable to hear some complaints for violating the implicit social contract of the game: that's a grimdark Gygaxian trap, not a Big Time Heroes trap.

[Unoriginal]

Keep in mind that 5e doesn't consider falling into lava to be insta-death.

By the DMG, being submerged in lava is 18d10 damages. Which is impressive, but on average isn't going to kill a lvl 10 fighter.

[hymer]

I deliberately put the trap in an unfair, two-rolls-and-you-die format, to see what suggestions, dice-based or no, people had for improving its fairness.
I think I'd make sure that the instant death nature of the trap was known to the players. I might go so far as to state it DM to players if the hints or clues didn't seem to make it clear. And I'd put it in a place they might like to go (say, for some big bonus treasure), but which they would not need to go. Then they can decide whether they think it's worth taking the chance, and they can put all their collective ingenuity into mitigating the risk if they should decide it's worth trying.

[Temperjoke]

If I'm understanding correctly, you actually have three checks involved with this trap:

Check A: Performing the ritual
Result 1: Successfully perform the ritual
Result 2: Just miss passing the check, initiates the trap
Result 3: Fails miserably, no immediate danger, but next attempt is more likely to fail

Check B: Notice the trap
Result 1: Realize that there is an illusion covering deadly trap
Result 2: Fail to notice the illusion

Check C: Fall into the trap
Result 1: Death

What sort of indicators are you giving the players? For example, on Check A, does the door give them a response or a warning if they get Result 3? Such as saying "Begone simpleton, death lies beyond this portals for fools who fail." On Check B, what happens if they realize there is an illusion? Do they have a way to reset the door? Or are they completely screwed? What if they create a bridge over the pit? Can they still continue on their way?

Let's say they fail to notice the illusion, but don't trust this innocent hallway and take precautions that would prevent them from falling (like casting levitate to avoid trap buttons), what happens then?

Something also to consider, has the right expectations been set? I don't mean by a session zero or anything, I mean by the setting. Have they been dealing with traps on a constant basis in this dungeon, or is this the only actual trap? Does this place have a reputation they could have learned about?

[MagneticKitty]

If anything I would make them obviously optional. Off the main path. And baited with a great prize if they manage to best the trap. Maybe like a treasure at the bottom of an acid lake. Magic so it doesn't tarnish. With many half dissolved bodies around.

Something where they don't feel pressured to do it. I would never mandate a Insta kill trap. Maybe give them 3 chances (akin to death saves). Arcana to dispel the trap if magic. Slight of hand to disarm it, dex to dodge it, athletics to break it, survival to figure out how to navigate without tripping it, let then come up with the skills they want to try to use, and you decide if it makes sense. Maybe history to see if they've read about the trap. Make it a skill challenge. You may let them know how difficult the trap is ahead of time.
Easy 10, med 15, hard 20dc
Where they can try any of these but once they pass or fail 3 times the trap is resolved in death or a prize. Let them know once they start they cannot stop and that the penalty is death before they start. Make sure to distinguish from normal traps

[Catullus64]

OP, I have one question: do you consider spells like Disintegrate or Power Word Kill fair?

Fair in the hands of players? Absolutely. One NPC or monster swiftly and immediately killed in exchange for a high-level spell slot? No big deal, not going to break any story which has been at all planned out.

As something to throw at players? Ehhhhhh... they do seem to border on unfair, yeah, although Disintegrate less so, since it involves both save and damage.

Standards of "fair" in this game should always be biased in favor of the players. If the monsters got five or six rolls to avoid falling into a deathtrap the players put effort into setting, they'd justifiably pelt me with dice.

[Unoriginal]

Fair in the hands of players? Absolutely. One NPC or monster swiftly and immediately killed in exchange for a high-level spell slot? No big deal, not going to break any story which has been at all planned out.

As something to throw at players? Ehhhhhh... they do seem to border on unfair, yeah, although Disintegrate less so, since it involves both save and damage.

Standards of "fair" in this game should always be biased in favor of the players. If the monsters got five or six rolls to avoid falling into a deathtrap the players put effort into setting, they'd justifiably pelt me with dice.

Then it seems to me you have a solid grasp on what you, personally, consider fair or unfair at your table, and so that you know the answer to your question about how to make this trap fair.

I hope it's useful.

[mephnick]

OP, I have one question: do you consider spells like Disintegrate or Power Word Kill fair?

Absolutely. The players have a responsibility to understand that these things are on the table and that NPCs will do anything to survive, just as they will. But I also consider "save and die" fair and so did D&D for decades before it wussed out when players forgot that characters were tools and not imaginary friends. Your soul won't shrivel into nothingness if your character dies. Just make a new one.

Plus, any trap that doesn't instantly kill or seriously maim its target isn't a very good trap, is it? You have to make it obvious that messing this up will kill you before the character attempts it, but a single failed save and instant death is fine, as long as the players understand it's possible beforehand.

[MrStabby]

I think it is important to give all players a chance to shine.

Religion and arcana both key of intelligence- (And spotting illusions) better might be a religion check then a strength check to grab onto something to not fall in.

I also like the idea of practical instant death rather than immediate death. For example 20d10 poison damage per turn till a con save is passed will finish most low level characters, I like that it leaves open options for being a dwarf nd having high con and a party healing you till you recover. It helps other ways of making character features be relevant.

[Vogie]

For me, I like the Angry GM's posts about traps and doing them right. Establishing a foreboding, but audible "click" of traps in general, allowing players to still have some reaction- and roleplay- based agency in the face of said trap.

A really cool trap that is badly executed is like trying to convince your player that it isn't "Rocks fall, everyone dies" scenario because they were actually artisanally crafted imported marble that fell, not merely "rocks". It's not going to work.

[smcmike]

Instead of worrying about whether something is fair, worry about whether it is fun.

Most traps are not fun, including the example discussed above. It isn’t helpful to think of a character as being “two rolls from death,” as if all rolls are created equal.

[strangebloke]

Absolutely. The players have a responsibility to understand that these things are on the table and that NPCs will do anything to survive, just as they will. But I also consider "save and die" fair and so did D&D for decades before it wussed out when players forgot that characters were tools and not imaginary friends. Your soul won't shrivel into nothingness if your character dies. Just make a new one.

Plus, any trap that doesn't instantly kill or seriously maim its target isn't a very good trap, is it? You have to make it obvious that messing this up will kill you before the character attempts it, but a single failed save and instant death is fine, as long as the players understand it's possible beforehand.

I agree with your post, but I'd like to reiterate: Death is an inconvenience past level five. Barring a globe of annihilation, it's just not that big a deal.

Unless the pack of morons couldn't be arsed to buy a scroll of revivify the last time they were in a town.

[Merudo]

I think the Tomb of Horrors campaign is the golden standard in instakill traps.

I almost every case, death by an insta-kill trap is the fault of poor decisions on the part of the player, not just one or two unlucky dice rolls.

[Gullintanni]

I think the Tomb of Horrors campaign is the golden standard in instakill traps.

I almost every case, death by an insta-kill trap is the fault of poor decisions on the part of the player, not just one or two unlucky dice rolls.

This hits the nail squarely on the head. 3.5 took a relatively poor route with trap design - namely one of binary skill checks. Traps ought to be encounters. For example, perhaps the PCs enter a room, hit a trip wire, and the walls start closing in, leading to potentially flattened PCs. The DM could then describe visible moving gears nested in the ceiling above the walls that clever PCs could could jam. Or perhaps spikes portrude from the walls that are large enough to be climbed, enabling vertical escape. Open Locks could be used to try and get through the doors, or a sufficiently strong character (and/or a few strength buffs from the casters) might be enough to smash the exits open.

In any case, you'd get a spot check to notice the trip wire, a disable device check to disable the trip wire, and if you trigger the trap, multiple routes by which to avoid an otherwise lethal hazard.

Traps should come with solutions that reward creative thinking, rather than simply punishing poor luck.

In the case of the golden door, I would forego the requirement for Knowledge (Religion) entirely. Hide instructions for performing the ritual somewhere in the dungeon, and let the party stumble across them. Let the party put 2 and 2 together, and try to figure out that performing the ritual in front of the door is the key. Or, allow someone with Knowledge (Religion) to make a check to see if they know the ritual without having to find detailed instructions.

Have opposing forces try to mislead the party into performing the ritual incorrectly, triggering the lethal trap, and give the party opportunities to catch those opposing forces in the act along the way. Rather than have the party step through the door and fall into lava, have the entrances to the room lock down, spouts from the wall open, and start pouring lava into the room. Let the party come up with a solution.

[MrStabby]

Instead of worrying about whether something is fair, worry about whether it is fun.

Most traps are not fun, including the example discussed above. It isn’t helpful to think of a character as being “two rolls from death,” as if all rolls are created equal.

I think that traps, done right, can not just be fun but also add a lot to a campaign. The XGtE complex traps are awesome for fun by themselves.

The OP trap, whilst maybe not yet optimised for fun, does convey a lot about the world, the faction in question and helps add to the tension of the whole campaign.

[Random Sanity]

There is no such thing as a "fair" way to one-shot-kill a PC.

[MaxWilson]

Plus, any trap that doesn't instantly kill or seriously maim its target isn't a very good trap, is it? You have to make it obvious that messing this up will kill you before the character attempts it, but a single failed save and instant death is fine, as long as the players understand it's possible beforehand.

Therefore, a DM should either:

(1) Make good, deadly, unfun traps, OR

(2) Construct a universe to play in such that a plethora of bad, fun traps should logically exist.

I invented Trap Gremlins for this purpose. They're highly-magical but singlemindedly creatures which are attracted to deserted places like dungeons and to good food left out after midnight, and they make gimmicky traps and then polymorph into the form of common objects and sit around watching for creatures to fall into their traps. If you disarm or otherwise defeat, the nearby Trap Gremlin that created the trap splatters into goo as if it had been squished by a huge invisible mallet, thus explaining why beating a trap yields XP. If you simply trigger the trap with a zombie or something, either the trap resets instantly or the gremlin eventually gets around to creating another, depending on the nature of the trap.

[DMThac0]

There are two types of traps if you want to look at it in a simplified sense:

1: the kind that keeps people out of places they shouldn't be, for a very good reason = deadly (horn of orcus in a temple would have this kind of trap)

2: the kind that are used for capturing or subduing elusive prey that are to be kept alive: snares, nets, locking doors, etc.

---

The trick here is to know which one belongs where and make sure the players understand what is going on.

If you want them to travel to the bottom of an inverted ziggurat to obtain an artifact that could cause world wide chaos, yea make sure the players know that the traps are going to kill them...period.

If the players are going to try to enter the lair of cannibalistic gnomes who like to torture their victims before making them dinner...the traps are going to cause damage, and otherwise incapacitate them.

There is also something to be said about available technology/resources: Goblins probably won't be able to make an intricate trap that drops the players into a room with collapsing walls. Generally, a Lich isn't going to use something so simple as hand crossbows linked to trip wires as their traps.
---

Traps are not unfair, the way they are presented is. If the players are caught, with no form of warning, then it's a bad trap, deadly or not.

[Lunali]

One thing you should always consider when making traps, how do the owners of the traps interact with them?

In this case, if the owners make a mistake in their ritual they will most likely not notice any difference between what they expect to see and the illusion. They will then not interact with the illusion until it's time to make their dex save to avoid dying. With the penalty for failure being so high, it's unlikely that the DC of the ritual would be high enough for the failure by 6 or more to ever be an issue.

If you wanted to use this trap, I would suggest instead making the ritual rather simple, but the scroll detailing it be in a language that the PCs don't know. If they have access to comprehend languages or the like, make the scroll partially destroyed. Elsewhere in the room you could have depictions of the ritual that would require religion/arcana/investigation rolls to figure out, probably along with depictions of what happens if it is done incorrectly.

[LaserFace]

Instakill traps are only good with specific types of tables.

Highly lethal dungeon crawl with medium-to-high level characters where everyone rolled up a backup character? One ability check and one save is fine.

Game with a bunch of level 1 characters played by 12-year-olds? Low level narrative-focused game with backstories and special miniatures and commisioned portraits? Forget about it.

Somewhere in between? ...Somewhere in between.

In general, traps are lame. Use complex traps as outlined in Xanathar's and combo them with a regular encounter. Acid gas trap? Boring. Golem? Boring. Golem fight inside an acid gas trap? NOW you're talking.

I came to say essentially this. Except I didn't think of Acid Gas Golem Trap and now I want to play that.

[Snails]

This hits the nail squarely on the head. 3.5 took a relatively poor route with trap design - namely one of binary skill checks. Traps ought to be encounters. For example, perhaps the PCs enter a room, hit a trip wire, and the walls start closing in, leading to potentially flattened PCs. The DM could then describe visible moving gears nested in the ceiling above the walls that clever PCs could could jam. Or perhaps spikes portrude from the walls that are large enough to be climbed, enabling vertical escape. Open Locks could be used to try and get through the doors, or a sufficiently strong character (and/or a few strength buffs from the casters) might be enough to smash the exits open.


There are pros and cons to the 3.5 design. The big plus is that it may be a single roll, but getting hammered by the trap is usually only a big inconvenience and very rarely death.

The way you describe does work well...at a cost. It requires a DM who is consistent in his or her manner of describing rooms, and is patient when the players dither in an odd room because some random thing spooked them into pulling out the ten foot poles and anti-trap kit. Oh, look, twenty minutes of valuable gaming time down the drain. Are we having fun?

It can work, but it is not for everyone.

[LudicSavant]

All death is ultimately down to dice rolls.
This is a gross oversimplification. There are many ways to make something less luck-based and more skill-based, even if it uses an RNG somewhere in the equation.

It's not really about the number of die rolls... even something that allows no save at all can potentially feel fair (and there are plenty of examples of things that can cause instant death in games with no RNG at all). What really matters for making something feel more skill-based than luck-based is if the player could have made meaningful choices to avoid their fate based on information reasonably available to them.

[Snails]

As for the trap as described by the OP, in the 5e world of flat math I would say it is a terrible design.

Basically everyone has a 25% of failing in the 1 to 5 range -- greater skill means greater chance of outright succeeding, NOT a greater chance of not tripping the trap.

Once triggered, people with good Investigate (Int) will have a ballpark 40% of falling into lava. Everyone else has a greater than 40% of dying.

That does not HAVE to be true. But would you ever set DCs for a lava death trap in the 11 to 13 range? Wouldn't make sense, given the implied effort required to create this trap.

[DeadMech]

I think a few posts touch on this. You don't want to blindside the players with this sort of thing. Not unless you actually want to kill PC's.

Like with the suggested situation of a treasure on a pedestal in the middle of a pool of acid. Us here we're all fairly certain approaching this and grabbing the treasure is a bad idea. Genre savy newcomers to dnd probably recognize that approaching this is a bad idea. Someone suggested describing how when the party throws something into it, that something ceases to be a something very quickly. I wouldn't shy away from slipping in game terms. Saying that the pool of acid reduced a goblin corpse to steaming sludge the moment it bobbed back up to the surface only to collapse into goo indistinguishable from the rest of the pool tells you that the acid is dangerous. But this is a game. Things that obliterate corpses or kill goblins are a dime a dozen. Even the greenest players aren't going to mistake it though when you say half under your breath 20d8 acid damage when you roll some random dice behind the screen to simulate dealing damage to that corpse. They know how much hitpoints they have and they know 20-160 is almost certainly going to be more than that. I wouldn't even feel bad about being meta about it. Player characters understand their world better than players might.

Something else you could do that could be applied to you gate is to have the party come across someone who's encountered the particular death trap before. This guy used to be an adventurer like you. Maybe he's a fighter or something. He came to this gate with his party. Doesn't really understand the hocus pocus stuff the wizard talked about or the preachy stuff the paladin was on about. The gate told the wizard off and not to try again if he knew what was good for him but the paladin managed to open it. At least they all thought he did. Maybe the fighter didn't see what happened cause he was busy standing past the previous door looking down the hall they came in from to make sure no one was following them. Just heard something that sounded like a paladin swearing,first and last time he's heard a paladin swear. By the time fighter comes over the first thing he noticed is the smell. The wizard cast levitate to pull the paladin out... but all he fished up was a drooping dripping white hot piece of slag that used to be part of the paladin's chestplate while the gate mocked the would be intruders. Fighter retired and went back to bouncing bars after that. Party now knows the trap is serious business. They have some clues what it does and what they have to do with it. If someone runs through the illusory hall after this without taking precautions then there is very little else you could have done to stop it.

I will bring up the point again though to carefully consider if you want instakill traps in your game. Even the one will beat a serious case of paranoid into your adventurers. And it's a tough mindset to shake. You can tell I've seen that sorta of thing before and the people I play with now haven't. Considering I was the one half though telling them not to touch the treasure chest while looking for something to use as a makeshift ten foot pole before our wizard jumped ontop of and hugged the mimic. It was quick but it wasn't pretty.

[Terdarius]

I would like to add that your trap will potentially be a dud fun wise.
If the players succeed their ritual check, there is no sign of a trap at all and possibly no hint as to what would have happened if they failed.
This is mechanically the same as the trap never have been there at all.
In fact it might persuade some DMs to make the DC impossibly high to make sure they trigger the trap otherwise what’s the point, right? (if it wasn’t an insta kill one at least)

Think of Indiana jones when he carefully walks through a trapped corridor but triggers it anyway and then has to figure out how to escape its certain death outcome. How would it have been if he avoided the trap completely? It wouldn’t even be in the movie, because it would have been just him walking through a corridor with nothing happening.

In my opinion a good trap is an encounter to overcome, just like a combat or RP encounter.
It should involve players making decisions, being creative to solve the problem and involve multiple dice rolls and possibly drain their resources, but most importantly be fun!
So, the players should not just stumble into a binary situation of nothing happens or you die.
It should be a complete encounter that takes creativity to overcome with a potential lethal outcome.

I’m just spit balling here, but you could make the door require a certain artifact to be present during the ritual, (something the players do not have) or the door “wakes up” and starts “attacking” the people that have started the ritual without the proper key. (completing the ritual still opens the door though)

To make sure someone is not just stuck casting the ritual for the whole encounter I would require the ritual to have at least one person “channeling” but it is possible for the whole party to channel at the same time. So, if your party is made of 5 players they could get in 5 channels per round if everyone channels. If people are distracted (concentration check) and or otherwise occupied the ritual is slowed down.

For example, the ritual takes a total of 25 rounds of a person channeling (so if every character channeled every round it takes 5 rounds to complete the ritual) and every round the door tries something (increasingly difficult) to interrupt the players and make the ritual fail. At the end the door should make a last ditched effort to prevent the ritual from completing making It a race against time somehow (several successful ability/skill checks needed to finish before the door kills a character or the party)

Some examples of what the door could possibly do:
- Cause a small earthquake (Dex Save or fall down taking a small amount of damage and interrupting the channel)
- Summon a monster to attack the players (this is probably the most boring since it turns it into a combat encounter)
- Slide a protective 2nd door in front of it using some kind of mechanism, that the players need to disable or the door will be inaccessible even if the ritual is completed.
- Create a storm outside the door to hinder players in some way, potentially doing damage
- Use illusions to trick the players
- Etc. Be creative

So, surviving the ritual and seeing it through to the end is the encounter.