D&D (2024) Learning 2024 D&D rules by converting classic 1e Greyhawk encounters to 5e

[Saracenus]

So, I am converting and updating a classic adventure for my next adventure campaign I am DMing. The example below taught me how hiding, surprise, and perception works in D&D 2024.

Spoiler: Gary Gygax's Original Dungeon Key Entry From A 1e Adventure

1. POOL
The following encounter should challenge a party of 5-8 characters of 1st or 2nd level. If fewer characters are present, or if 2nd level characters are lacking (one or none), the DM should decrease the number of monsters accordingly, first omitting one of the larger creatures, then the smaller, leaving one large monster at all times. Do not, however, add to the number. If the characters are all 2nd or higher level, convert small monsters to large specimens.

Roll 1d6; six giant frogs herein surprise intruders on a result of 1-4. These nasty things leap from their lurking places in the tall weeds near the edge of the pool, to a maximum range of 12 ". They attack madly, for they are voraciously hungry at all times.

If characters are mounted, check to see if the horses panic and throw their riders or plunge into the marsh and become mired. The chance of panic is 90% for most mounts, but only 10% for a warhorse. If panic occurs, the chance of either subsequent occurrence is 50% (check for each, per horse; both may occur to one victim).

Each of the two larger frogs has a tongue 12 feet long; the smaller tongue is a mere 6 feet. If its prey is more than 5 feet away, a frog uses its tongue to attack (gaining a + 4 "to hit" bonus, but for no damage). Any victim hit by the tongue may attack it, and if successful the frog withdraws it and does not use it thereafter. Otherwise, the victim is pulled in by the tongue. A victim weighing more than the frog is dragged in at half speed, gaining a second attempt to hit the tongue. Each of the small frogs weighs about 100 pounds; each of the larger, 200.

For added fun, each frog can swallow an elf, halfling, or small human if its "to hit" roll is 20. The victim has three tries to escape if an edged weapon is in hand; a score of 18 or more is required for success (indicating that the frog is slain). After three failures, a swallowed victim dies.

The largest frog has swallowed an amethyst (worth 100 gp), but the others are penniless.

[Ommited the 1e Giant Frog stats]

MH1. POOL​

Lurking in the tall weeds near the edge of the pool are one Giant Frog per member of the party, max six. They are submerged and hidden (they have the Invisible [Condition]) waiting for unsuspecting prey to pass by. They are voraciously hungry and will attack anything in range.

A Passive Perception 19 score or an active Wisdom (Perception) check DC 19 examining the pool will allow a PC to see them before they attack. Otherwise, they attack with Surprise and get Advantage on their Initiative check and Advantage on their first round attacks. NOTE: Any Surprised characters have Disadvantage to their Initiative checks.

If the characters are mounted during the initial attack, have them make a Charisma (Animal Handling) check, with Disadvantage if they are surprised, to prevent their mounts from panicking and either throwing their riders or plunging into the marsh and becoming mired:

• Warhorse - Very Easy, DC 5
• Riding horse - Easy, DC 10
• Untrained horse or a nag purchased from the Traders (see area H13. WOODEN BUILDING WITH SHUTTERED WINDOWS (Trading Post)) - Hard, DC 20

5e Statblocks:
* Giant Frog (1-6, CR 1/4)

Adjusting The Difficulty:
This encounter is meant to be a normal challenge a party of 4-6 PCs and hirelings at 2nd level. If the party is 1st level this will be a potentially deadly encounter and consider scaling the number down to 1 to 1.5 Giant Frogs per 2 PCs and hirelings.

Treasure:
* 1 Giant Frog has swallowed an amethyst worth 100 gp.

 

[bedir than]

So, I am converting and updating a classic adventure for my next adventure campaign I am DMing. The example below taught me how hiding, surprise, and perception works in D&D 2024.

MH1. POOL​

Lurking in the tall weeds near the edge of the pool are 1 Giant Frog per member of the party, max 6. They are submerged and hidden (they have the Invisibility Condition) waiting for unsuspecting prey to pass by. They are voraciously hungry and will attack anything in range.

A Passive Perception 19 or an active Wisdom (Perception) check DC 19 examining the pool will allow a PC to see them before they attack. Otherwise, they attack with Surprise and get Advantage on their Initiative Check and Advantage on their attack.

If the characters are mounted during the initial attack, have them make a Charisma (Animal Handling) check, with Disadvantage if they are surprised, to prevent their mounts from panicking and either throwing their riders or plunging into the marsh and becoming mired:

• Warhorse - Very Easy, DC 5
• Riding horse - Easy, DC 10
• Untrained horse or a nag purchased from the Traders (see area H13. WOODEN BUILDING WITH SHUTTERED WINDOWS (Trading Post)) - Hard, DC 20

5e Statblocks:
* Giant Frog (1-6, CR 1/4)

Adjusting The Difficulty:
This encounter is meant to be a normal challenge a party of 4-6 PCs and hirelings at 2nd level. If the party is 1st level this will be a potentially deadly encounter and consider scaling the number down to 1 to 1.5 Giant Frogs per 2 PCs and hirelings.

Treasure:
* 1 Giant Frog has swallowed an amethyst worth 100 gp.

This is a fun way to go about applying the new system. Good job

 

[Saracenus]

Just showing my math for the hide “check” by the frogs.

Normally you roll for it to see if something can hide if they are Heavily Obscured (I am considering the murky pond heavily obscured and the PCs could not see what is in it) or behind Three-Quarters Cover or Total Cover. Since they hid before the PCs show up, I used a Passive Stealth check (10+4 = 14) plus added in Advantage (additional +5 for passive) for the frog's natural camouflage in a murky, reed strewn pool with only their eyes are above the surface. Thus, I gave them a DC 19 for Passive Perception or active Wisdom (Perception) check to notice them.

You could make the argument that they do not have Advantage and thus roll a d20 prior to the encounter to see if the Giant Frogs actually hid themselves. They have Stealth +4 (should be +3, but that didn't make it into the errata) and roll a d20 and if they make a DC 15 hide check they have the Invisible Condition. Whatever the successful check result was is the DC to perceive them (basically somewhere between 15 and 24). They would basically have a 45% chance of success in hiding prior to the encounter.

The mid point calc between 15 and 14 is 19.5. So, without including the chance of failure I think that a DC 19 is just fine.

 

[Shiroiken]

So, I am converting and updating a classic adventure for my next adventure campaign I am DMing. The example below taught me how hiding, surprise, and perception works in D&D 2024.

Cool. As someone who runs old adventure's, I love this idea.

MH1. POOL​

Lurking in the tall weeds near the edge of the pool are 1 Giant Frog per member of the party, max 6. They are submerged and hidden (they have the Invisibility Condition) waiting for unsuspecting prey to pass by. They are voraciously hungry and will attack anything in range.

A Passive Perception 19 or an active Wisdom (Perception) check DC 19 examining the pool will allow a PC to see them before they attack. Otherwise, they attack with Surprise and get Advantage on their Initiative Check and Advantage on their attack.

Quick clarification: the characters that don't use the Search Action and succeed on the check would be surprised and have disadvantage on initiative. If no one succeeds at this, then the frogs have advantage as well (per the Invisibility condition). While not as brutal as losing an entire round of actions, being ambushed is still really bad.

 

[Saracenus]

Cool. As someone who runs old adventure's, I love this idea.

Thanks! I love Obsidian! It makes linking everything a dream.

Quick clarification: the characters that don't use the Search Action and succeed on the check would be surprised and have disadvantage on initiative. If no one succeeds at this, then the frogs have advantage as well (per the Invisibility condition). While not as brutal as losing an entire round of actions, being ambushed is still really bad.

So, if a character has a awesome Passive Perception and beats the DC 19 is still surprised if they attack? The only way to see them is to take a Search [Action] outside of combat? What did I miss in the rules?

I see that the Surprised combatant gets Disadvantage on initiative but isn't someone who can make a passive perception check is aware of the enemy, correct?

 

[Shiroiken]

So, if a character has a awesome Passive Perception and beats the DC 19 is still surprised if they attack? The only way to see them is to take a Search [Action] outside of combat? What did I miss in the rules?

I see that the Surprised combatant gets Disadvantage on initiative but isn't someone who can make a passive perception check is aware of the enemy, correct?

Passive Scores are used when you don't want to reveal information by calling for a check. You still have to take the Search Action to use Perception, per the PHB.

I've deiced to edit to go into more detail and show my work.

In the PHB, under actions, it talks about doing anything outside of moving and conversing requiring an action. It give examples of using these actions outside of combat, particularly in social and exploration encounters.

In the DMG, under Perception, it talks about using Passive Scores when you don't want to give the players information by calling for a roll. It doesn't say anything about not using the action.

 

[Saracenus]

Passive Scores are used when you don't want to reveal information by calling for a check. You still have to take the Search Action to use Perception, per the PHB.

I've deiced to edit to go into more detail and show my work.

In the PHB, under actions, it talks about doing anything outside of moving and conversing requiring an action. It give examples of using these actions outside of combat, particularly in social and exploration encounters.

In the DMG, under Perception, it talks about using Passive Scores when you don't want to give the players information by calling for a roll. It doesn't say anything about not using the action.

On one level by RAW you are correct. I an not sure what the RAI is as the developers are not in the thread with us.

But, a Passive Perception score gives the creatures awareness of their surroundings. My RAF ruling would be to the following,
1) Make the character(s) aware that, "something seems off around the pond, but you are not sure what it is."
Then, 2) Ask them to make a Search [Action], Wisdom (Perception) check to see if they can actually see something.

To me that seems more in line with how it should work plus it makes my players unsettled and paranoid . They could still blow the active Search action and be surprised by the attack.

I think this strikes the right balance of rewarding a player for an amazing Passive Perception score and still giving the Giant Frogs a chance to do what they do best, leap and swallow small party members.

Here is the cleaned up section with my RAF ruling...

A Passive Perception 19 will make the character aware something is wrong around the pool, but they cannot tell what it is. A Search [Action] Wisdom (Perception) check DC 19 examining the pool will allow a PC to see the frogs before they attack. Otherwise, the frogs attack with Surprise and get Advantage on their Initiative check and Advantage on their first round attacks. NOTE: Any Surprised characters have Disadvantage to their Initiative checks.

I want to thank Shiroiken for a wonderfully clarifying conversation on this topic.

 

[Saracenus]

Added a spoiler tag to the OP containing the original Gygax text from the adventure as some whipper-snappers here may not have read it before.

 

[Shiroiken]

On one level by RAW you are correct. I an not sure what the RAI is as the developers are not in the thread with us.

RAI becomes tricky, because even the official rules guru for 2014 was wrong about how Passive Perception worked. He made the mistake of carrying over the way it worked in 4E, when the rules were written completely differently. One could argue that as the rules guru his interpretation was correct RAI, no matter how much it differed from the actual rules (and the interpretation of the lead designer).

But, a Passive Perception score gives the creatures awareness of their surroundings.

This is the way it worked in 4E, but the 2024 rules don't actually say this anywhere (at least, not to my knowledge; please correct me if I'm wrong). I'm pretty sure it didn't in 2014 either, but a lot of people made that assumption. There's nothing wrong with playing it that way, and it worked really well in 4E. I just point out the inconsistency whenever I come across it, because most people think this is RAW (plus I held this against Crawford for years during 5E, so I'm probably a bit bitter about it).

I want to thank Shiroiken for a wonderfully clarifying conversation on this topic.

You're absolutely welcome! I love the project you're doing, so I'm glad to help

 

[Azzy]

This is the way it worked in 4E, but the 2024 rules don't actually say this anywhere (at least, not to my knowledge; please correct me if I'm wrong).

Passive Perception. Sometimes your DM will determine whether your character notices something without asking you to make a Wisdom (Perception) check; the DM uses your Passive Perception instead. Passive Perception is a score that reflects a general awareness of your surroundings when you're not actively looking for something.