It depends on whether you want to enable the
player to have a role in detecting and/or disabling the trap (beyond just saying, "I check for traps" and "I attempt to disable the trap"). What you have is enough to narrate the results of plain vanilla skill checks.
What I
think [MENTION=20323]Quickleaf[/MENTION] is suggesting with his questions is the possibility of allowing the PC an increased* chance of success (up to and including success without a roll) based on the ingenuity of the player. Personally, I think that is more fun, but it does mean more work in preparing (or being quick enough to improvise) the details of the trap, particularly the trigger mechanism.
* I guess you could also decrease the chance of success (up to and including failure without a roll) based on a more detailed action declaration by the player, but I'm not sure that increases the fun. Except that you might get to kill the PCs. Ok, maybe it does increase the fun.
I agree with allowing the PC's actions to modify the success chances, including automatic success. But I think that is a DM skill or approach and not something that can be written into the trap description itself in a concise way. Such a detailed description would at least require 4 or 5 sentences and possible several paragraphs. I think that's beyond what a "publish" level adventure should detail (besides, you will always miss some clever idea of the PCs).
That being said, I do try to provide some detail on what the perception check reveals. Note that I don't say the trap is detected, I say that you notice holes in the ceiling. This is part of my approach, and I think is close to a consensus as to the best way to approach trap detection and passive perception. This is why an investigation check is needed. You notice something amiss, now you need to figure out what that means.
...
If the PCs just check the door for traps without noticing the holes, is it still DC 10?
Up to the DM to adjudicate. But my normal approach would be that you need to do a perception check before you investigate. i.e. why are you trying to figure out what is wrong if you have yet to notice that something is wrong?
Now, as Shiroiken implies, if the party searches (perception check) the door and not the area around it, then you could reveal the switch and not the holes. Though I'm loathe to try and detail every possible action, and reasonable rulings for them, this is one I might adapt. See comments on rulings.
For this kind of case, you would want to be more explicit about how the darts would target the creatures in the affected area; that is, not all 24 darts will attack each creature (I assume).
That's why the damage is not 24d4. I intend that the trap is designed to spread the darts out evenly among the 4 squares (ten foot square) in front of the door.
I strikes me that disarming is only one kind of countermeasure. There can be others that have nothing to do with the trigger mechanism. For instance, in this case one could plug up or cover the holes, and it might be good to have guidance on how solid the plug would have to be, or how sturdy the covering would have to be.
I don't think a trap write can, or should, try to cover every approach that the players can come up with. I think giving the idea of what the trap is, then leave it up to the DM to make rulings. For instance, if the players said they held a large shield (or table, or dead body) over their heads when they open the door, I would make a ruling that they are not affected by the darts. It would also be up to the DM to rule what happens if they block the holes, or if they shoot corrosive acid up the holes, or if they transmute mud to rock and then back to rock after deforming the holes.
.... For the second, I think the assumption is that enough darts affect the area that everyone is attacked once. For such a method, a Dex save is more common than an Attack.
This is a good point. Not sure what is better. I was basing it on a spear trap which is a single attack roll.
Trigger and Actions seem to be a subset of Type. Both are part of Type function while Detection and Disarming seem more player character driven. With a Trap, Detection and Disarming will come into play only if the PP is high or the player rolls dice defeating the detection DC. I would order the events with the assumption that the trap will do what it is meant to do. However, I put the PP at the top and jump below if the player meets the condition for Detection.
Good feedback but I will disagree that the Type should contain mechanics other than a classification. All creatures have a type, and that only tells us if they are humanoids (and race) or beasts, or etc. Type as used by NPCs is just a classification, no other NPC (and I see traps and hazards as being closely related to NPCs) has any type of trait, action or ability included in its "type".
As for the order, I agree that perception should go first because there is always passive perception. Then instead of assuming the trap does what it is designed to do, I assume the players succeed at what they do. Therefore they detect something is wrong and investigate. Both work, and I did lay it out originally the other way, but I think in most cases assuming the players succeed in their perception check is the right way to go. But, both work.
An Example; (adjusted)
Dart Trap (Above Door/PP-14)(If PP14 is met I goto Detection and Disarming below)...
I don't like the PP shorthand, and thing the name should only contain the name.
Though the heading of "Lethality" works. Again I chose to stay in line with the NPC headings and call it an action. I think their is value in trying to keep things common when possible. I guess this means one could argue that Trigger should then go under Reactions, and that might be ok too.
On CR and XP:
I suppose you could give traps Hit Dice to help calculate CR/XP.
I would think the CR should also depend on the difficulty of detecting and disarming the trap - that's sort of the trap's defensive CR.
I really like this idea. I don't see CR/XP value for the example trap in the first post. Did you forgo this idea? CR can easily be replaced by DC and is perhaps more meaningful.
I would suggest that XP should be awarded for surviving the trap, not just detecting and disarming the trap. Maybe not as much as detecting and avoiding, but something. I reward XP to my players for surviving combat encounters, not just slaying opponents.
I really haven't laid this out yet. That's why I didn't include anything on this. Need to compare whatever we come up with the categories listed in the DMG, but they again don't give XP, only setback/deadly/etc.
I don't think HD work for calculating this since that not how anything else works in 5E.
I think damage for offensive CR and detection and disarming for defensive make sense. But, what are those values?
I haven't though this through yet, but a brainstorm on defensive CR:
For the base detection method, give 1 point for each value over DC over 10 (i.e. DC minus 10 equals points). Then for the the base investigation method do the same thing. Repeat for disarming.
This would typically give a range of 1-30. Divide this total by 4 to get the CR...
That would typically give CR's from 0 to 15. (Assuming of course max DC of 20, which might not be the case for a legendary trap, but that would still scale and work). Of course it gives a linear relation between DCs and CR... Is that good or bad I don't know.
