D&D 5E SPIRIT GUARDIANS range clarification

[Hriston]

Whats nonsense is your interpretation that something that is 'an X radius around a person (the caster)', can literally be inside the person if the caster is bigger than X. Or now you're trying to argue the magic also shrinks the caster to fit inside it as well as the spell effect.

Your interpretation leads to an absurd result, and thus is to be ignored, in favor of one that doesnt.

I interpret globe of invulnerability's "around you" to mean "centered on you" with respect to the 10' radius of the barrier. This agrees with the interpretation that the shape of the globe is a sphere as indicated by both the word globe and the specification of a 10' radius emanating from the caster as the point of origin. It also agrees with the rules for spherical areas of effect which state, "The sphere's size is expressed as a radius in feet that extends from the point" which tells us how big the sphere is, and that "A sphere's point of origin is included in the sphere's area of effect" which tells us that no matter how big the point of origin is, it doesn't make the sphere any larger than what has been defined by the radius.

 

[DND_Reborn]

No. I can say 'there are no burglars within a 50m radius of this city block' which is one of the examples used.

It means there are no burglars within 50m of the city block, and the block is square.

You can use radius, not in strict geometry terms, but something 'radiating' from something.

Sigh...

So, here is the corner of your city block (blue) and your "within 50m" (orange) and a burglar (red dot):

Obviously, the burglar is not within 50m. "Radiating out" from the corner of the block (a point) is the same thing as radius of 50m from that point...

You are using radius wrong.

No, I am not.

More specifically, you are taking one geometrical use of radius that you happen to be aware of, and declaring that any other use is wrong.

It is the only applicable meaning unless you want to discuss the bone definition.

That isn't evidence you are right. That is evidence you only know of some uses of the word radius.

It is entirely evidence I am right, but more importantly the point I've been stating ad nauseum is that there is no need to use the word "radius" in spell.

Any wedge of a circle can be said to have a radius, not just circles. So can any curve -- this is known as the radius of curvature.

Sure, never said it was only applicable to a circle.

If you want a formal geometrical definition, radius around a non-point object can be mathematically described by creating a derived metric where the distance between any two points in the object is defined to be zero, and that "short cut" can be used to measure distances between other points. Then do the usual equivalence classes of neighborhoods.

This reduces the object to a single point in a metric space, and we can now define a sphere of radius 15' around that single point. All points in this modified metric space correspond to points in the space we derived it from, so we can map this back to the original space.

If the original object was (say) a 5' cube, the 15' radius sphere centered on that 5' cube is a 20' radius cube with rounded corners. Those rounded corners have a radius of curvature 15'.

Is that mathematical enough?

Sure, if you really felt you had to go that far, which IMO is just damn silly. But that is exactly what the images I've posted have shown... like the one above.

I suspect not; I suspect you aren't actually interested in radius as a mathematical concept other than insofar as it supports your position. But, if you are only using radius as a mathematical concept insofar as it supports your position, then radius as a mathematical concept doesn't support your position.

Actually, it does. Again as shown in my posts. But regardless my point has been for many posts now that removing radius and using the term within or zone would work better and avoid most (if not all) of these issues.

Time for Thanksgiving dinner. Cheers.

 

[NotAYakk]

I interpret globe of invulnerability's "around you" to mean "centered on you" with respect to the 10' radius of the barrier. This agrees with the interpretation that the shape of the globe is a sphere as indicated by both the word globe and the specification of a 10' radius emanating from the caster as the point of origin. It also agrees with the rules for spherical areas of effect which state, "The sphere's size is expressed as a radius in feet that extends from the point" which tells us how big the sphere is, and that "A sphere's point of origin is included in the sphere's area of effect" which tells us that no matter how big the point of origin is, it doesn't make the sphere any larger than what has been defined by the radius.

The point of origin is "self".
The point of origin is included in the area of effect.
A 10' radius centered on "self" thus includes "self", as "self" is the point of origin.
A 10' radius sphere is at most 20' long on any axis.
A 10' radius spell cast by a 30' by 30' creature has "self" as its point of origin, and that is included in the area of effect.
Conclusion: A 30' by 30' creature is thus less than 20' long on any axis.

Math is fun. ^_^

 

[Voadam]

So when I say 'You are not allowed to enter within a 10' radius around that Football stadium', you interpret that to mean 'I cant enter a 10' circle inside the stadium and in the middle of it?'

I would interpret it as you using the term radius incorrectly and actually meaning "you are not allowed to enter within 10' of that football stadium."

I hope you never get a restraining order placed on you, because the above would be a breach of the order.

I would expect most legal document restraining order terms not to be phrased casually or imprecisely. I would expect them to be phrased to prohibit coming within x distance of a prohibited area or person and not a radius around something.

 

[Flamestrike]

I would interpret it as you using the term radius incorrectly and actually meaning "you are not allowed to enter within 10' of that football stadium."

Radius doesnt just apply to geometry, it's also used to describe a general volume or area:

Definition of radius​

noun, plural ra·di·i [rey-dee-ahy], ra·di·us·es.
a straight line extending from the center of a circle or sphere to the circumference or surface:The radius of a circle is half the diameter.
the length of such a line.
any radial or radiating part.
a circular area having an extent determined by the length of the radius from a given or specified central point:every house within a radius of 50 miles.
a field or range of operation or influence.
extent of possible operation, travel, etc., as under a single supply of fuel:the flying radius of an airplane.

Definition of radius | Dictionary.com

In this case, the 'radius of X' extends out from the caster, and surrounds the caster to a distance of X.

You dont start measuring from the casters internal organs. You start measuring from the caster, with the radius extending X feet in every direction, from the caster.

For Spirit Guardians, cast by a Gargantuan (20x20') creature (16 total squares), that means it extends (or radiates) a further 15' from those 16 squares in every direction.

 

[Flamestrike]

So, here is the corner of your city block (blue) and your "within 50m" (orange) and a burglar (red dot):

View attachment 267775

Obviously, the burglar is not within 50m. "Radiating out" from the corner of the block (a point) is the same thing as radius of 50m from that point...

The burglar isnt within 50m of the area that radiates out from the city block, so he's not within the 50m radius.

We dont measure the 50m that radiates out from the city block from the centre of the block though. We're not using the term geometrically, we're using the term in a plain, natural language of 'an area that radiates out from the city block, 50m in every direction', which is an area that this burglar is NOT in.

 

[Flamestrike]

I interpret globe of invulnerability's "around you" to mean "centered on you" with respect to the 10' radius of the barrier.

My caster is Gargantuan (25'x25') space, and 50' tall. Are you saying that when I cast Globe of invulnerability, the area 'around the caster (me)' is not in fact, around me at all, and is somewhere inside of me?

The 10' radius radiates 10' around the caster. Any interpretation that leads to the radius not radiating 10 'around the caster' is clearly a misinterpretation because it expressly defeats the clear wording of the spell and creates absurdities, where you end up with something that is not, in fact radiating 10' around the caster.

 

[Rya.Reisender]

No, its an issue both ways.

With no grid it is still either 15 feet from the center of the gargantuan dragon cleric or 15 feet extending from both ends of the 50 foot long dragon.

In your example if you are 15' 3" from the center of the cleric you are within 15' of the edge of the cleric. Not really a big issue that will come up for normal size people casters the way it would when measured in five foot square increments, but the difference on ridiculously giant casters could be narratively significant.

Without a grid, I'd simply always go from the creature's center. I'd assume any creature no matter what size is just a dot just with a larger area of control. So your actual size doesn't matter in regards to the size of the AoE.

The reasons I have for this:
1. There nothing in the rules that says that if the point of origin is a creature, it ignores the mathematical definition of a point and assumes the creature's physical size.
2. Nowhere in the rules it is specified how fat or wide a creature really is.
3. It would be super annoying to calculate the AoE.
4. Most, if not all, spellcasters with this or a similar spells are normal size anyway.

(Interestingly on a grid if you use creature's center as point of origin, the AoE is actually larger for a large creature compared to a normal sized creature because more grid cells would be half-covered.)

 

[Hriston]

My caster is Gargantuan (25'x25') space, and 50' tall. Are you saying that when I cast Globe of invulnerability, the area 'around the caster (me)' is not in fact, around me at all, and is somewhere inside of me?

The 10' radius radiates 10' around the caster. Any interpretation that leads to the radius not radiating 10 'around the caster' is clearly a misinterpretation because it expressly defeats the clear wording of the spell and creates absurdities, where you end up with something that is not, in fact radiating 10' around the caster.

As I've said, one way to reconcile the first clause of the first sentence of globe of invulnerability, "An immobile, faintly shimmering barrier springs into existence in a 10-foot radius around you", with the spell's stated range of "Self (10-foot radius)" and the implications of the attendant rules for Range (PHB 202) and Areas of Effect (PHB 204-5), when the spell is cast by a creature that doesn't fit inside a 10' radius sphere, is to describe the 10' radius shimmering globe as appearing in the place formerly inhabited by the creature, with the creature appearing inside the protective bubble. The idea in my mind is that the globe is "bigger on the inside" to accommodate the caster.

Another way is to interpret around to mean centered on and to describe the 10' radius sphere at the center of the space controlled by the caster, but without the warping of space inside the sphere, and thus having the sphere appear at the center of the caster's body-mass. Depending on the shape of the caster, the sphere could protrude outside part of its body, protecting its internal organs. Alternatively, the barrier could fail to come into existence in such a situation because it isn't large enough to contain the creature whose body blocks some or all lines of expansion from the point of origin to the radius of the AoE. I think this approach is undesirable because of these problems.

Alternatively, as you seem to prefer, you could say the barrier comes into existence 10' from the surface of the caster's body and that the shape of the AoE is not a sphere. The problems created by this approach are that you have to determine exactly where that surface lies which is not given anywhere in the rules and that you have to describe the "globe" as non-spherical. Both of these outcomes for me are also undesirable.

 

[Flamestrike]

No, your interpretation leads to absurd results, like a large enough caster casting a spell that creates a 'faintly shimmering barrier 10' around the caster' to actually create it inside of him.

If I told you: 'Heat is emanating from that (40' radius) bonfire out to a 20' radius around the bonfire', do you take that to mean that the heat is contained entirely within the bonfire, or do you take it to mean the heat is radiating out from outer edge of the bonfire, 20 feet in every direction?

Like I cant be bothered arguing this anymore. Rule however you want. In my games spellcasting Giants and Dragons and similar dont have 3/4 of their body sticking out of a 10' globe of magical energy. They get exactly what the spells says it gives them, a faintly shimmering barrier that springs into existence in a 10' radius around them (all of them) or 10 feet out from the outer edge of the space they occupy in every direction.