D&D 5E XGE rules on using thieves tool proficiency for finding traps

[iserith]

As both sets of rules mention finding a hidden object, and neither are more specific than general as they both mention the exact same thing - determining if there is, and where that item is - making two checks to do the exact same thing neuters characters.

A Rogue cannot be an expert at finding/removing traps at first level based on your style of play.

Not that I think it's a particularly good argument, but I would say rules for traps and secret doors are more specific than the general rules for Intelligence (Investigation) checks. So if we're going by the rules of specific beating general, I think I have the point.

You also appear to be conflating tasks with checks which aren't the same thing. As I said upthread, a typical trap interaction isn't 3 checks - it's 3 tasks which may involve 0 to 3 checks. A rogue at 1st level in my game doesn't need to be an expert in all three tasks. He or she has other members of the party to find traps or figure out how they work or, failing that, work together with the rogue on those tasks which imparts advantage if there's a check. Further I'm not sure a 1st level character is really much of an expert at anything or why I should expect them to be.

With regard to Investigation, I think the key word in the entry for this is "make deductions." If you're looking around for clues that are hidden, they are hidden objects and Wisdom (Perception) applies if there is a check. Making a deduction about what those clues mean, once you've found them, is Intelligence (Investigation) if there is a check. I think to some degree how one interprets Investigation comes down to whether the group or DM comes from a tradition of D&D 3.Xe where Search was an Intelligence-based skill used to find traps and secret doors. While I did play D&D 3.Xe for 8 years prior to D&D 4e, I cannot find justification within the rules I quoted above to use Investigation in this way.

 

[jgsugden]

Investigation is intelligence based and involves looking for clues and making deductions. A clue is not an object. A clue is the significance of an object. You first have to spot the object to have a chance to utilize it in investigation. It speaks to using your intellect to figure something out. It is how you USE data, not how you collect it.

Perception is wisdom based and is your ability to perceive something that does not fit, but has nothing to do with understanding the significance of it.

How do they work together? You need both perception and investigation success in order to locate, and then understand, something (whether a trap, a secret door, or to deal with any other mystery. HOWEVER, both can be used passively. Meaning that you can automatically succeed on these rolls without spending any effort if your passive scores are high enough.

HIDDEN PIT TRAP: You need a DC 14 Perception check to spot it. We don't even both mentioning the DC 5 Investigation check necessary to understand how it works, because it is obvious. If you want to stop it from collapsing when walked upon, that might be a Thieves Tools Check, a Carpenter's Tools Check, or something else - The DM and the Player bounce ideas together.

SWINGING BLADE TRAP: You step into a room and see swinging blades. They're obvious. You don't need to roll a perception roll because a someone with a 1 Wisdom and disadvantage on the roll would have a passive high enough to get the DC 1 Perception check, However, figuring out how to disarm it ... that is tricky. To get it to hold might require a very high tool check.

POISON GAS TRAP IN A CHEST LOCK: You Need a DC 17 Perception check to see the mechanism for it. Once you see it, you need a DC 15 Investigation check to figure out how it works. You need a DC 20 Thieves Tool check to disable it. It is entirely possible your passive Perception and Passive Investigation could be high enough that you would not need to roll. If not, DMs are going to create a better experience if they consider all your rolls and allow success on an earlier roll to either lower the DC (or give you advantage / a bonus) on a later roll. For example, Bob the Rogue passively sees the mechanism. He says he wants to take a closer look. He rolls a 20 for a total perception check of 30. The DM thinks that is high enough to make the investigation check easier, and tells Bob that he sees a gear based mechanism and a glass cylinder suspended over a container of liquid. He gives Bob advantage on his investigation, which raises his passive investigation above 15, allowing him to automatically figure out that it is a poison gas trap. Bob says he wants to figure out exactly how it works, so Bib rolls an Investigation and gets another 20, giving him an Investigation of 23. The DM gives Bob advantage on a roll to disarm the trap after describing that one of the gears appears loose, and knocking it out of position would prevent the trap from springing.

It makes sense when you think about the questions, "How hard is it to spot that there is something unusual?" and "How hard is it to figure out how it works?" That'll tell you what rolls need to be rolled, and which can be passively successful.

 

[bedir than]

Still, having three checks means that someone with Thieves Tools, who knows how to disarm traps, may have a low INT and somehow not know how to disarm traps. The same thing could happen with Perception and Investigation - despite Investigation clearly calling out that you can find hidden objects, the low WIS rogue would not be able to find a hidden object

 

[iserith]

Still, having three checks means that someone with Thieves Tools, who knows how to disarm traps, may have a low INT and somehow not know how to disarm traps. The same thing could happen with Perception and Investigation - despite Investigation clearly calling out that you can find hidden objects, the low WIS rogue would not be able to find a hidden object

There are other people in the party who can do these things or work together with the rogue for advantage. You seem to be operating from an assumption that the rogue must do all three tasks alone.

 

[bedir than]

There are other people in the party who can do these things or work together with the rogue for advantage. You seem to be operating from an assumption that the rogue must do all three tasks alone.

There are other members of the party that can swing swords. That doesn't mean a system which says a fighter can't swing a sword makes sense.

 

[iserith]

There are other members of the party that can swing swords. That doesn't mean a system which says a fighter can't swing a sword makes sense.

Right, but can you point me to a rule in the books that underpins your assumption such that a team working together on exploration challenges doesn't make sense to you?

 

[bedir than]

Right, but can you point me to a rule in the books that underpins your assumption such that a team working together on exploration challenges doesn't make sense to you?

While working as a team makes sense, I don't think the rogue should be required to work in a team to be an effective trap-finder/disabler.

The trope of the rogue ranging forward to find and remove traps is common in the fiction and goes back 4 decades within the game.

 

[iserith]

While working as a team makes sense, I don't think the rogue should be required to work in a team to be an effective trap-finder/disabler.

The trope of the rogue ranging forward to find and remove traps is common in the fiction and goes back 4 decades within the game.

So the rogue that wants to be that guy or gal has to invest in their build accordingly (expertise in Investigation and Perception) and perhaps sometimes spend Inspiration for advantage from time to time. Maybe buy a magnifying glass. Or take 10x the amount of time on the action as normal to get automatic success if possible. That's not going to be all rogues though, if we're using the rules as they are outlined in the books. I set my expectations accordingly as a player and DM.

 

[bedir than]

So the rogue that wants to be that guy or gal has to invest in their build accordingly (expertise in Investigation and Perception) and perhaps sometimes spend Inspiration for advantage from time to time. Maybe buy a magnifying glass. Or take 10x the amount of time on the action as normal to get automatic success if possible. That's not going to be all rogues though, if we're using the rules as they are outlined in the books. I set my expectations accordingly as a player and DM.

You forgot that they would also have to invest in skill and expertise in Thieves Tools in your interpretation.

Because you've ignored that Investigation is used for discovering hidden traps, per the rules.

 

[iserith]

You forgot that they would also have to invest in skill and expertise in Thieves Tools in your interpretation.

Because you've ignored that Investigation is used for discovering hidden traps, per the rules.

I don't think expertise in Thieves' Tools is necessary. They'll presumably already have a good Dexterity. Some traps by default don't even call for a check to disable them.

For some traps, the DM could say that Intelligence (Investigation) is needed to resolve a task to deduce the presence of the trap based on the DM's description of the environment ("variations in the mortar and stone of the floor") or the DM could say that it's needed to resolve a task to deduce what needs to be done to sabotage the trap after it has been found. If the rogue doesn't have expertise in Investigation, he or she may still not be as good at the party's wizard at this task which goes against your preference that the rogue be the character that exclusively deals with the traps. That's just how the rules are written. Outside of a dedicated build, teamwork is the key to success here.