D&D (2024) Learning 2024 D&D rules by converting classic 1e 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.

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 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 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.

 

[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?