Nondetection vs Shielded Mind

[No brains]

I've realized I may have made a mistake in another thread by saying a couatl could benefit from shapeshifting into humanoids that can innately cast nondetection, but in doing so forgot that the couatl always has the shielded mind ability. The abilities are very similar, so I can't help but wonder: which is the better of the two and is it really better to have both? I am calling upon our mightiest rules-wizards to divine what edge cases these abilities might help with.

Shielded Mind: The couatl is immune to Scrying and to any Effect that would sense its emotions, read its thoughts, or detect its Location.

vs

Nondetection: For the Duration, you hide a target that you touch from Divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can't be targeted by any Divination magic or perceived through magical Scrying Sensors.

The standout difference is that nondetection (when not limited to a self-only casting) can be used to shield objects and areas.

One area of nuance is in the difference between 'immune to' and 'can't be targeted by'. Ignoring how MtG handles that difference, what are some consequences of being immune to something you can be targeted by and being susceptible to something that can't target you?

Do we know of any divination magic that do not detect emotions, thoughts, or locations?

Another question, does immunity to effects that determine location grant immunity to other effects of the spell? For example, could Detect Evil and Good tell that there is a couatl around, but be unable to figure out where it is? Would mindspike deal no damage to a couatl?

Can anyone else help me think about whether or not a couatl should be paranoid enough to turn into a deep gnome 3 times a day?

[kazaryu]

I've realized I may have made a mistake in another thread by saying a couatl could benefit from shapeshifting into humanoids that can innately cast nondetection, but in doing so forgot that the couatl always has the shielded mind ability. The abilities are very similar, so I can't help but wonder: which is the better of the two and is it really better to have both? I am calling upon our mightiest rules-wizards to divine what edge cases these abilities might help with.

by virtue of being always active shielded mind is better, imo. even if you rule that a couatl would otherwise show up via scrying sensor, the use of nondetection on a location is...pretty weak protection if you're trying to hide a person. its mostly there to let you hide a thing. otherwise there's not a good reason to not simply cast nondetection on the creature.

Another question, does immunity to effects that determine location grant immunity to other effects of the spell? For example, could Detect Evil and Good tell that there is a couatl around, but be unable to figure out where it is? Would mindspike deal no damage to a couatl?

the big problem here is that the couatl feature is rather generically written. it doesn't spell things out as well as nondetection does. for my part, i read shielded mind as being, effectively, a permanent mindblank. in practice i actually take it a decent bit further than that, but that gets into homebrew territory, at least insofar as divination magic is concerned.. (also, a couatal wouldn't take damage from mindspike anyway, its immune to psychic damge).

Can anyone else help me think about whether or not a couatl should be paranoid enough to turn into a deep gnome 3 times a day?

i don't really see a thing that a nondetection does that the couatl can't do itself, outside of target an area. but it doesn't really need to make a 10foot area nondetectable, only itself. and with its truesight it could see if someone was scrying on its location. I don't even think a couatl would appear on a scrying, even it it wasn't targetted on the creature itself.

[NecessaryWeevil]

Do we know of any divination magic that do not detect emotions, thoughts, or locations?

Scrying does not directly detect any of these things.

[Sigreid]

The way non detection is worded, it would arguably prevent a diviner's ability to swap D20 rolls, as that is clearly divination magic.

[No brains]

by virtue of being always active shielded mind is better, imo. even if you rule that a couatl would otherwise show up via scrying sensor, the use of nondetection on a location is...pretty weak protection if you're trying to hide a person. its mostly there to let you hide a thing. otherwise there's not a good reason to not simply cast nondetection on the creature.

One benefit to nondetection being cast on objects is that nondetection can be cast on a 10-foot object that can then hold up to 8 medium creatures. A self-only nondectection doesn't grant this benefit, but a couatl could shapeshift into a giant constrictor snake and then wrap around a creature, maybe? Either way, yes, it does seem at the outset that shielded mind is better.

the big problem here is that the couatl feature is rather generically written. it doesn't spell things out as well as nondetection does. for my part, i read shielded mind as being, effectively, a permanent mindblank. in practice i actually take it a decent bit further than that, but that gets into homebrew territory, at least insofar as divination magic is concerned.. (also, a couatal wouldn't take damage from mindspike anyway, its immune to psychic damge).

The couatl also seems to have some enchantment that harms my reading comprehension. I think there are ways to swap damage types for spells, but I guess it's good that couatls have double protection. Just out of curiosity, how far would you take a couatl's shielded mind beyond permanent mind blank?

i don't really see a thing that a nondetection does that the couatl can't do itself, outside of target an area. but it doesn't really need to make a 10foot area nondetectable, only itself. and with its truesight it could see if someone was scrying on its location. I don't even think a couatl would appear on a scrying, even it it wasn't targetted on the creature itself.

The one thing I've imagined that nondetection helps with that shielded mind does not is that it is still possible to foretell a couatl's actions. Augury, Divination, Commune, and Contact Other Plane can still answer questions about couatls that do not pertain to its thoughts, emotions or location. This means you can still learn of a couatl's actions and you can learn a little of its claims and intents by checking against another source. If a couatl needs to go deep cover beyond the veil of prophecy, getting a self-only Nondetection would help.

Scrying does not directly detect any of these things.

Couatls are also expressly immune to scrying.

The way non detection is worded, it would arguably prevent a diviner's ability to swap D20 rolls, as that is clearly divination magic.

I would have to call that like an 'Air Bud technicality'. Sure it's a wizard doing something fantastical related to the school of divination, but the effect never describes itself as magical. I can't really think of a way right now how that can be something other than magic, but apparently it isn't. Superposition cheese or something, I don't know.

[kazaryu]

One benefit to nondetection being cast on objects is that nondetection can be cast on a 10-foot object that can then hold up to 8 medium creatures. A self-only nondectection doesn't grant this benefit, but a couatl could shapeshift into a giant constrictor snake and then wrap around a creature, maybe? Either way, yes, it does seem at the outset that shielded mind is better.

sure but that doesn't really benefit the couatl, the couatl is safe regardless. thats the frame of reference i was using.

The couatl also seems to have some enchantment that harms my reading comprehension. I think there are ways to swap damage types for spells, but I guess it's good that couatls have double protection. Just out of curiosity, how far would you take a couatl's shielded mind beyond permanent mind blank?

lol. and not 'would'. do. essentially i extend that protection to basically any form of magic that might learn anything about them. for example a cobalt soul monks extrac aspects would fail against couatl (in my setting). the truevision granted by the trueseeing spell would fail to detect their shapeshift. any homebrewed mechanics i might use for like...studying a corpse, or to determine the properties of a scale/feather the party might find would similarly fail.

basically i have a small group of couatl roaming my game world (well, technically several, but 1 specifically that PC parties are likely to encounter). they're there as a sort of...like extended easter egg. the first time the party meets them they get the idea that something is weird (due to how they talk/act) and if they really push it, can eventually uncover the mystery, and potentially earn themselves incredibly useful allies in the process. but i make it difficult to just...magic information about them.

The one thing I've imagined that nondetection helps with that shielded mind does not is that it is still possible to foretell a couatl's actions. Augury, Divination, Commune, and Contact Other Plane can still answer questions about couatls that do not pertain to its thoughts, emotions or location. This means you can still learn of a couatl's actions and you can learn a little of its claims and intents by checking against another source. If a couatl needs to go deep cover beyond the veil of prophecy, getting a self-only Nondetection would help.

ehhh....i don't think any of those spells target the couatl. you're essentially calling up a third party in all those instances, and asking what they think.

[Tanarii]

Depends if you think nondetection prevents use of Commune or Contact Other Plane to ask questions about the coatl.

[Chronos]

Both abilities are full of rules holes. A couatl is immune to the Scrying spell, but is it immune to the similar but lower-level Clairvoyance, which never actually uses the word "scry"? If a couatl turns invisible, and someone casts See Invisibility or True Sight, can they see it? Do spells like Commune and Divination, used to ask questions about a couatl, count as "targeting" it? What about Legend Lore? What if the couatl is just mundanely hiding using the Stealth skill, can you use Perception to try to find it? That'd be "an effect that determines its location", and Shielded Mind doesn't specify magical effects.

[kazaryu]

Both abilities are full of rules holes. A couatl is immune to the Scrying spell, but is it immune to the similar but lower-level Clairvoyance, which never actually uses the word "scry"? If a couatl turns invisible, and someone casts See Invisibility or True Sight, can they see it? Do spells like Commune and Divination, used to ask questions about a couatl, count as "targeting" it? What about Legend Lore? What if the couatl is just mundanely hiding using the Stealth skill, can you use Perception to try to find it? That'd be "an effect that determines its location", and Shielded Mind doesn't specify magical effects.

ehhh, some of this is veering well beyond the bounds of natural language. specifically the stealth question. that one definitely isn't protected by shielded mind, because thats not what anyone is going to be talking about when they say 'effect'.

[Chronos]

That one? Probably not. But the line between Perception and other effects is very fuzzy. What if someone was under Enhance Ability (Owl's Wisdom), and only made their Perception check because of the advantage? Enhance Ability is definitely an "effect", and it enabled determining the couatl's location. Or what if they rolled too low at first, but then used the extra die from Guidance or Bardic Inspiration? What if it was a high-level rogue trying to spot the couatl, but their roll was really low, and they only saw it because of Reliable Talent?

[Corran]

One area of nuance is in the difference between 'immune to' and 'can't be targeted by'. Ignoring how MtG handles that difference, what are some consequences of being immune to something you can be targeted by and being susceptible to something that can't target you?

I think the question should be if being immune to something offers anything more than simply being untargettable by it. And in this particular example I would think of scrying. Not sure if that's RAW, but I am tempted to say that being immun to scrying means you are not seen or heard at all when inside an area someone is scrying over. While being impossible to be targeted by a scrying spell would not prevent you from being seen or heard by any divination magic that does not target you (eg using a scrying spell on an area).

Do we know of any divination magic that do not detect emotions, thoughts, or locations?

I cannot think of any non divination spells that would do any of such things, at least RAW. But there are abilities that are not explicitely called out as divination magic (although that's what they logically are) which shielded mind would definitelly block, while non detection might or might not block depending on DM ruling. Such as a sprite's heart sight or a nothic's weird insight (there are probably more but these are the ones I can recall).

It's worth noting that there are non-divination spells that open up some divination possibilities depending on how much the player is willing to push for it and on how much the DM is wiling to allow. Such as contingency (which is how Larloch survived the fall of Netehril).

Another question, does immunity to effects that determine location grant immunity to other effects of the spell? For example, could Detect Evil and Good tell that there is a couatl around, but be unable to figure out where it is? Would mindspike deal no damage to a couatl?

I would say that immunity to the effect means that the spell does not interact with your at all, even if it does not target you. So IMO detect good would not reveal anything about the coulat.

Can anyone else help me think about whether or not a couatl should be paranoid enough to turn into a deep gnome 3 times a day?

As you said, items can be tracked down. So if you dont want to be tracked then you either mask them with non detection or you dont keep them around. Also, if you location or your companions might be known to someone who could scry on you, non detection could help prevent scrying in the first place. Even if shield mind does end up making you unable to be sensed by divination magic, the actions or responses from people who dont share shielded mind could very well betray important parts of your conversation.

[kazaryu]

That one? Probably not. But the line between Perception and other effects is very fuzzy. What if someone was under Enhance Ability (Owl's Wisdom), and only made their Perception check because of the advantage? Enhance Ability is definitely an "effect", and it enabled determining the couatl's location. Or what if they rolled too low at first, but then used the extra die from Guidance or Bardic Inspiration? What if it was a high-level rogue trying to spot the couatl, but their roll was really low, and they only saw it because of Reliable Talent?

but things like enhance ability or bardic inspiration aren't 'effects that determine the creatures location'. its still the perception (i.e. looking around carefully) that determines the creatures location.

[Temperjoke]

I think it depends on the situation. If the coatl is trying to hide a macguffin, for example, nondetection would block locate object, while I interpret that the coatl's native powers does not. I wouldn't give nondetection to every coatl, but having one who specializes a little more would make sense in a group of them.