Jon Gilliam
Explorer
Let's return to the scenario again where you've deceived an enemy into believing you're an ally. Let's say you meet the guy in the tavern, chat him up, and crit on a Deception. He now believes you mean him no harm.
The next day, you encounter him again, walk up to him, and attack. You already did your Deception check yesterday. Certainly people aren't continuously doing Insight checks every time them meet someone again to see if they've had a change of heart and now intend to murder them. Does that succeeding on that one-time Deception check gain you the permanent opportunity to surprise that opponent anytime you like?
In order to keep that from happening, you'd have to presume that creatures are always using passive Insight to counter a possible Deception, but that sounds much less reasonable than using passive Perception to always be on the lookout for something hidden that's going to attack you. With something Hidden/Stealthy, it's already presumed that the fact that they're hidden alone gives suspicion that they might mean harm, and justifies why someone's passive Perception would be continually alert to anything and anyone coming at them with stealth.
But, that's not the case with Deception. Once successfully deceived, why would a creature be wary enough to justify countering with passive Insight? And would you have to do another Deception check the second time you encountered this creature if you intend to surprise them, even though they were previously deceived? With hiding, it's clear why you need to do a Stealth check before surprise, but with Deception it's not.
Another problem is that there's no clear point to do the surprise determination. Let's say the rest of the party is hidden and you approach a foe trying to deceive: "Hey, hey - I'm your friend here, you've misunderstood..." That calls for an out-of-combat Insight vs Deception check, since you could be trying to start a parlay with your opponent.
But when do you do this passive Insight vs Deception check to determine surprise? It's clear for Stealth - once everyone's hidden, surprise can be determined. The only point of determination for surprise with Deception would be when the creature being deceptive decides to attack, but at that point they've already done the check. Surprise is meant to be something done by hiding as a group, and it's not meant to have a "triggering" creature who must decide at what point they intend to attack before surprise is determined.
If surprise-by-Charisma could be a thing, why wouldn't high-Charisma characters want to do it more often for surprise rather than hiding? Would they have to be visible to do this Deception, or would it be enough to lie convincingly unhidden but still behind cover? Could you use the "message" cantrip to deceive an opponent and still be hidden at the same time, and take the best of your Stealth check and your Deception check?
If RAW intended these other mechanisms for surprise, the rule would have been written something like this:
"The DM decides who might be surprised based on whether they notice a threat. As soon as any combatant intends to attack, the DM asks for a skill check using the skill each creature is employing to keep from being noticed as a threat and compares that to the passive score of the opposing skill of each creature on the opposing side"
But that's not what it says, and to take the rule to mean that RAW is explicitly giving discretion under RAW to decide surprise by other means would have the DM required to decide on the spot both the checks necessary and the conditions that initiate surprise being determined, all without any guidance from the rules.
Look at Hiding, something the DM is meant to decide on the spot with only guidance from the rules. The rules make that clear, and they provide guidance in the form of the Hiding side-box on p. 177. If there was guidance in the rules as to how a DM should run surprise other than Hiding vs Stealth, then I'd agree that's what RAW intended, but there's not.
I've done my best to be open to idea and to try to give opposing arguments a fair shake. But, at least right now, I just find absolutely no persuasive argument that Surprise was meant to be determined as anything but by Hiding, and no rules to help me as DM to make sure I'm being fair to players who might build their character concept on Stealth when deciding surprise on anything but that basis.
The next day, you encounter him again, walk up to him, and attack. You already did your Deception check yesterday. Certainly people aren't continuously doing Insight checks every time them meet someone again to see if they've had a change of heart and now intend to murder them. Does that succeeding on that one-time Deception check gain you the permanent opportunity to surprise that opponent anytime you like?
In order to keep that from happening, you'd have to presume that creatures are always using passive Insight to counter a possible Deception, but that sounds much less reasonable than using passive Perception to always be on the lookout for something hidden that's going to attack you. With something Hidden/Stealthy, it's already presumed that the fact that they're hidden alone gives suspicion that they might mean harm, and justifies why someone's passive Perception would be continually alert to anything and anyone coming at them with stealth.
But, that's not the case with Deception. Once successfully deceived, why would a creature be wary enough to justify countering with passive Insight? And would you have to do another Deception check the second time you encountered this creature if you intend to surprise them, even though they were previously deceived? With hiding, it's clear why you need to do a Stealth check before surprise, but with Deception it's not.
Another problem is that there's no clear point to do the surprise determination. Let's say the rest of the party is hidden and you approach a foe trying to deceive: "Hey, hey - I'm your friend here, you've misunderstood..." That calls for an out-of-combat Insight vs Deception check, since you could be trying to start a parlay with your opponent.
But when do you do this passive Insight vs Deception check to determine surprise? It's clear for Stealth - once everyone's hidden, surprise can be determined. The only point of determination for surprise with Deception would be when the creature being deceptive decides to attack, but at that point they've already done the check. Surprise is meant to be something done by hiding as a group, and it's not meant to have a "triggering" creature who must decide at what point they intend to attack before surprise is determined.
If surprise-by-Charisma could be a thing, why wouldn't high-Charisma characters want to do it more often for surprise rather than hiding? Would they have to be visible to do this Deception, or would it be enough to lie convincingly unhidden but still behind cover? Could you use the "message" cantrip to deceive an opponent and still be hidden at the same time, and take the best of your Stealth check and your Deception check?
If RAW intended these other mechanisms for surprise, the rule would have been written something like this:
"The DM decides who might be surprised based on whether they notice a threat. As soon as any combatant intends to attack, the DM asks for a skill check using the skill each creature is employing to keep from being noticed as a threat and compares that to the passive score of the opposing skill of each creature on the opposing side"
But that's not what it says, and to take the rule to mean that RAW is explicitly giving discretion under RAW to decide surprise by other means would have the DM required to decide on the spot both the checks necessary and the conditions that initiate surprise being determined, all without any guidance from the rules.
Look at Hiding, something the DM is meant to decide on the spot with only guidance from the rules. The rules make that clear, and they provide guidance in the form of the Hiding side-box on p. 177. If there was guidance in the rules as to how a DM should run surprise other than Hiding vs Stealth, then I'd agree that's what RAW intended, but there's not.
I've done my best to be open to idea and to try to give opposing arguments a fair shake. But, at least right now, I just find absolutely no persuasive argument that Surprise was meant to be determined as anything but by Hiding, and no rules to help me as DM to make sure I'm being fair to players who might build their character concept on Stealth when deciding surprise on anything but that basis.