Can an attacker tell they're dealing non-lethal damage?

Question

While reviewing regeneration I was reminded that "damage dealt to the creature is treated as nonlethal damage". This made me wonder if the attacker can tell (before regeneration happens) that the damage is non-lethal so that they may adjust their tactics etc.

So for example, if I encountered a troll and had never done so before, and struck it with a normal battleaxe...could I tell I was striking for non-lethal damage? Or would I be waiting to see its wounds bind before I knew something was up? You could argue that you might realize immediately, like when you remove the axe to strike again it's not the same as striking a non-regen creature, the gaps tighten slightly, etc so...

Similarly, in the same situation (not in water), let's take a scrag (type of troll), that only regens in water. The damage to it is non-lethal still but there would be no immediate visual regen effect because it's not actively regenerating (when not in water).

I realize this could be a question that boils down to opinion so book quotes/examples are welcome.

Maybe related: Could non-lethal damage draw blood?

Answer 1

Yes, you can tell

DMG p.26

When running a combat, make sure that you describe nonlethal and lethal damage differently. The distinction should be clear—both in the players’ imaginations and on their character sheets.

Does this only apply to damage the characters receive?

Personally I am happy to take what the rulebooks say at face value: "make sure that you describe nonlethal and lethal damage differently" is pretty unequivocal. Some people, however, like to keep their players in the dark about stuff like this.

With all due respect, these people are wrong because Poor Communication Kills and the role of the DM is to give the players adequate and sufficient information for them to make informed decisions about their characters that have reasonable consequences. This is called agency and it is the entire point of any RPG - if you want a game without agency Snakes and Ladders is cheap and has a much shallower learning curve. I have written about it in My PCs have a plan that will get them all killed; how and why should I save them? Playing games where you are denied the right to choose is not fun!

With respect to the specific example, if you keep this information secret then the players will have their decision making ability constrained to their detriment. The fight will be tougher (probably) than it would have been and result in more expenditure of resources by the party and possibly unnecessary casualties. This will mean fewer encounters before the party needs to rest and less fun all around.

If instead, you say, "You strike solidly with your sword and open a wide gash. You recoil in horror as the green muscle tissue writhes and begins to knit back together and the severed veins grope towards one another like some macabre game of blind man's bluff" the players have been given information that things are not as they expect. They now have more agency, more choices available which broadly speaking are to persist in what they would normally do or do something different. Now, they may make a good choice and save some resources or they may not but you will have enabled instead of disabling their agency.

Answer 2

No, you can't tell when inflicting said damage.

Dale M's quote from the DMG I believe is referring to damage received rather than inflicted (hinted at by the reference to 'character sheets'), that is to say, a character should know the difference between getting battered and being killed. Due to the nature of the game, the player has a very precise knowledge of just how battered or hurt your character is.

In the case of regeneration in particular, the damage dealt is lethal and only treated as non-lethal for the sake of regeneration mechanics. If/when the regeneration occurs it should be obvious at that point that the damage inflicted is less than permanent, but before that point the damage isn't any different.

I'd also argue for a 'show, don't tell' element here. You don't know the specific HP for a hostile monster, but that doesn't mean the DM can't indicate their general condition in more vague terms. It would be appropriate for the troll to perhaps not flinch, knowing it will regenerate, and naturally the wound will close up over time and make the regeneration more obvious as combat rounds go on. The trick is to have your players realize by themselves that the troll isn't going to fall to normal damage and a new approach is needed, rather than telling them outright.

The distinction in regeneration is suffering what would normally be lethal damage and recovering, rather than resisting the damage outright. Regeneration would not be as fast if the passage of time is reduced. Sufficient damage will fell them (if only temporarily).

Answer 3

So for example, if I encountered a troll and had never done so before, and struck it with a normal battleaxe...could I tell I was striking for non-lethal damage?

I cannot see a reason why you should, as a rule, be able to determine.

In this specific instance, I find it particularly implausible. How would a character, even a fighter used to using weapons professionally, who knows nothing about troll anatomy, the thickness of their tissue, etc. be able to tell from the split second of contact in a dangerous battle (as you imply with 'the gaps tighten slightly'), or subsequent fleeting observation whether the damage is liable to cause death if sustained or not?

The distinction between lethal and nonlethal damage is largely a game mechanic not a real-world one; almost all the examples in this answer could kill, and to split hairs slightly, the description of regeneration says that the lethal damage is converted to nonlethal damage (implied later as fire etc. doesn't convert) which is then healed. (On a careful reading I don't agree with Danikov that the damage remains lethal, "the creature automatically cures itself of nonlethal damage" implies that this damage is now definitely nonlethal, as does the use of 'convert' and the line "An attack that can cause instant death only threatens the creature with death if it is delivered by weapons that deal it lethal damage.").

By default, characters cannot even determine how wounded enemies are (although the players might know), except through means such as Deathwatch. As in real life, an assailant does not know what the effect of their attack might be until the victim collapses or similar.

If characters have a reason to think the damage they are dealing is nonlethal, if the players can describe how their characters trying to determine this then I'd perhaps allow a skill check in certain circumstances - for example a heal roll to determine if a creature is dead or unconscious (with severe penalties for unfamiliar races), or, at a higher DC, to get some description an opponent's injuries (the roll should be hidden so the players can't be entirely sure if the info is accurate). However you'd need to be careful not to eliminate the benefit of Deathwatch.

Answer 4

I'm pretty sure you should be able to tell. The closest rules source I can come up with has already been mentioned by Dale above (though I'll replicate it below in case something happens to Dale's answer), but while d20 has no expectation of complete transparency, a player should know the effects of their own attacks. I usually try to express unusual defenses both mechanically and descriptively - "The abomination doesn't appear to fear the flames; it is scorched in spots, but not as charred as you're used to making things with that spell. How much base fire damage did you say you did?" This tells them that their fire spell did less damage than expected in a way both the player and the character can understand it, without me specifying that the creature has resist fire 10.

For regeneration, some descriptive effects can be taken directly from mechanic rules: "The lumbering creature is nearly unaffected by the stabbing wound, appearing more irritated than wounded. No more blood gushes from its arm as you pull your sword free, the hole seeming to shrink before your very eyes. It takes the hit for 12, but you get the feeling you're not going to kill it that way. Figured out what it is yet?"

Quote for posterity's sake:

DMG p.26

When running a combat, make sure that you describe nonlethal and lethal damage differently. The distinction should be clear—both in the players’ imaginations and on their character sheets.