Emanation: radius or diameter?

Quote from jl8e >>

Quote from MaximusArael020 >>

Quote from Pantagruel666 >>

Quote from Squirrelloid >>

 Fair, but also unplayable.

Only really becomes relevant if you do something like casting darkness on a rope. 

 What a sec... are you saying that you could cast darkness on a 50ft rope, and if the rope were stretched out to its fullest length then you would basically have a "tube" of darkness that is 15 feet high, 30 feet wide,  and 80 feet long (15 feet emanating from either end means an additional 30 feet to the rope, so 80 feet)?

 Technically, that's what the rules say.

They really, really don't

darkness clearly states its Emanation extends from a single point. Whether that point is in space or is on an object doesn't impact the size of its AoE

Quote from AntonSirius >>

darkness clearly states its Emanation extends from a single point. Whether that point is in space or is on an object doesn't impact the size of its AoE

Try reading the actual text of the spell? "Alternatively, you cast the spell on an object that isn’t being worn or carried, causing the Darkness to fill a 15-foot Emanation originating from that object." Nothing there about it being a point; even if you're using space rather than actual object dimensions, casting it on a large object will give you a larger field off darkness than if you cast it on a point.

Is this intended? Doubtful, but it's clearly what the spell says.

Quote from AntonSirius >>

Quote from jl8e >>

Quote from MaximusArael020 >>

Quote from Pantagruel666 >>

Quote from Squirrelloid >>

 Fair, but also unplayable.

Only really becomes relevant if you do something like casting darkness on a rope. 

 What a sec... are you saying that you could cast darkness on a 50ft rope, and if the rope were stretched out to its fullest length then you would basically have a "tube" of darkness that is 15 feet high, 30 feet wide,  and 80 feet long (15 feet emanating from either end means an additional 30 feet to the rope, so 80 feet)?

 Technically, that's what the rules say.

 

They really, really don't

darkness clearly states its Emanation extends from a single point. Whether that point is in space or is on an object doesn't impact the size of its AoE

 An emanation extends in lines from the affected target, following the AoE rules. When that is a creature, if forms a circle extending outward from the edges of the creature. (Technically, this would be a rounded-corner square from a large or larger creature, but that's a level of fussiness that most people don't wanna think about. (And if this causes somebody to adjust their emanations, I hope they're having fun.))

With an object, it's usually similar, but the rope can be stretched out in a line which does, by the definition of emanations, mean that you get a huge length of easily-manipulable darkness generation, but, as I said, I'd be inclined to reign that in because it's not supposed to give you that many extra square feet.

The spell does give you the option of casting it on a point in space, but casting it on an object is an alternative targeting choice. If it were always meant to be a point, then it'd be a spherical radius, not an emanation.

My assumption is that it's an emanation because that's the standard 5.5e uses for a movable area attached to a creature or object, and they just didn't really think about the implications.

Quote from Pantagruel666 >>

Quote from AntonSirius >>

darkness clearly states its Emanation extends from a single point. Whether that point is in space or is on an object doesn't impact the size of its AoE

Try reading the actual text of the spell? "Alternatively, you cast the spell on an object that isn’t being worn or carried, causing the Darkness to fill a 15-foot Emanation originating from that object." Nothing there about it being a point; even if you're using space rather than actual object dimensions, casting it on a large object will give you a larger field off darkness than if you cast it on a point.

Is this intended? Doubtful, but it's clearly what the spell says.

You tell me to read the text of the spell, and then ignore half of it. Nice

For the duration, magical Darkness spreads from a point within range and fills a 15-foot-radius Sphere. Darkvision can’t see through it, and nonmagical light can’t illuminate it.

Alternatively, you cast the spell on an object that isn’t being worn or carried, causing the Darkness to fill a 15-foot Emanation originating from that object. Covering that object with something opaque, such as a bowl or helm, blocks the Darkness.

But wait, you say, one's a Sphere and one's an Emanation. That changes its total AoE!

No, it doesn't. Or at least, it shouldn't

An area of effect has a point of origin, a location from which the effect’s energy erupts. The rules for each shape specify how to position its point of origin.

The only difference between a Sphere and an Emanation is that the Sphere doesn't move, while an Emanation can travel with the creature or object it's radiating from. A 15-foot Sphere is exactly the same size as a 15-foot Emanation

Now, for convenience sake, do people normally just play an Emanation as though it extends in all directions from a whole "thing" instead of a point, increasing its AoE depending on the size of the thing emitting it? Sure. But that's not RAW. Per the DMG, when playing on a grid, the point of origin for an AoE -- which every AoE has, regardless of shape -- should be an intersection point on a map. Not an entire square or squares

An area of effect must be translated onto squares or hexes to determine which potential targets are in the area. If the area has a point of origin, choose an intersection of squares or hexes to be the point of origin, then follow its rules as normal. If an area of effect covers at least half a square or hex, the entire square or hex is affected.

If you cast darkness on a rope and then stretch out the rope, all you'll have is a standard 15-foot Emanation of darkness with rope sticking out of it

EDIT If there's some rule I'm unaware of that makes an Emanation an explicit exception to the general Area of Effect rules, that would be a different situation, of course

So, by RAW, if a Large creature has an emanation of 10ft., it would affect nothing other than the creature (if it chooses)? And you think that's intended?

In fact, I think we have a bit of specific vs general here. AoE rules do, indeed, say that all AoEs have a "point of origin", but then it goes on to say that each type describes that point. Well, only one of those types doesn't describe a point of origin: the emanation. It describes the creature or object as the source.

Quote from AntonSirius >>

Quote from Pantagruel666 >>

Quote from AntonSirius >>

darkness clearly states its Emanation extends from a single point. Whether that point is in space or is on an object doesn't impact the size of its AoE

Try reading the actual text of the spell? "Alternatively, you cast the spell on an object that isn’t being worn or carried, causing the Darkness to fill a 15-foot Emanation originating from that object." Nothing there about it being a point; even if you're using space rather than actual object dimensions, casting it on a large object will give you a larger field off darkness than if you cast it on a point.

Is this intended? Doubtful, but it's clearly what the spell says.

 

You tell me to read the text of the spell, and then ignore half of it. Nice

For the duration, magical Darkness spreads from a point within range and fills a 15-foot-radius Sphere. Darkvision can’t see through it, and nonmagical light can’t illuminate it.

Alternatively, you cast the spell on an object that isn’t being worn or carried, causing the Darkness to fill a 15-foot Emanation originating from that object. Covering that object with something opaque, such as a bowl or helm, blocks the Darkness.

 

But wait, you say, one's a Sphere and one's an Emanation. That changes its total AoE!

No, it doesn't. Or at least, it shouldn't

An area of effect has a point of origin, a location from which the effect’s energy erupts. The rules for each shape specify how to position its point of origin.

 

The only difference between a Sphere and an Emanation is that the Sphere doesn't move, while an Emanation can travel with the creature or object it's radiating from. A 15-foot Sphere is exactly the same size as a 15-foot Emanation

Now, for convenience sake, do people normally just play an Emanation as though it extends in all directions from a whole "thing" instead of a point, increasing its AoE depending on the size of the thing emitting it? Sure. But that's not RAW. Per the DMG, when playing on a grid, the point of origin for an AoE -- which every AoE has, regardless of shape -- should be an intersection point on a map. Not an entire square or squares

An area of effect must be translated onto squares or hexes to determine which potential targets are in the area. If the area has a point of origin, choose an intersection of squares or hexes to be the point of origin, then follow its rules as normal. If an area of effect covers at least half a square or hex, the entire square or hex is affected.

 

If you cast darkness on a rope and then stretch out the rope, all you'll have is a standard 15-foot Emanation of darkness with rope sticking out of it

EDIT If there's some rule I'm unaware of that makes an Emanation an explicit exception to the general Area of Effect rules, that would be a different situation, of course

One thing that's interesting from the text that you quoted is that it says "An area of affect has a point of origin...", but then for the DMG "playing on a grid" section, it says "IF the area has a point of origin...". If all areas of effect have a point of origin, it shouldn't say "if", because it's just talking about areas of effect. 

Interestingly, all the glossary descriptions of the area of effect shapes (cube, sphere, cylinder, etc) state explicitly that they have a "point of origin", EXCEPT the one for emanation, which says it "extends in straight lines from a creature or object."

I'm not saying I agree with either interpretation (the rope thing seems unintentional) but the wording choice is interesting.

Quote from AntonSirius >>

But wait, you say, one's a Sphere and one's an Emanation. That changes its total AoE!

No, it doesn't. Or at least, it shouldn't

An area of effect has a point of origin, a location from which the effect’s energy erupts. The rules for each shape specify how to position its point of origin.

Yea the designers screwed up when they added "Emanation" as an AoE. An emanation cannot do what it is meant to do if it is constrained by the same language as the other AoE's. Reading "point of origin" as "a single tiny specific point, of origin" works for the other AoE's because of how they spread but an emanation spreads from a creatures (or objects) full space instead.

A easy example is to look at the Paladin aura's. The 5.5E Paladin says "in a 10-foot Emanation that originates from you" while the 5E Paladin says "within 10 feet of you". The area that is covered by the aura really shouldn't differ between the editions but for that to be true then a 10-foot emanation cannot cover the same space as a 10-foot sphere. A 10-foot sphere should have a diameter of 20 feet but a 10-foot emanation should have a diameter of 25 feet (assuming a medium sized creature). 

Quote from Thezzaruz >>

Quote from AntonSirius >>

But wait, you say, one's a Sphere and one's an Emanation. That changes its total AoE!

No, it doesn't. Or at least, it shouldn't

An area of effect has a point of origin, a location from which the effect’s energy erupts. The rules for each shape specify how to position its point of origin.

Yea the designers screwed up when they added "Emanation" as an AoE. An emanation cannot do what it is meant to do if it is constrained by the same language as the other AoE's. Reading "point of origin" as "a single tiny specific point, of origin" works for the other AoE's because of how they spread but an emanation spreads from a creatures (or objects) full space instead.

A easy example is to look at the Paladin aura's. The 5.5E Paladin says "in a 10-foot Emanation that originates from you" while the 5E Paladin says "within 10 feet of you". The area that is covered by the aura really shouldn't differ between the editions but for that to be true then a 10-foot emanation cannot cover the same space as a 10-foot sphere. A 10-foot sphere should have a diameter of 20 feet but a 10-foot emanation should have a diameter of 25 feet (assuming a medium sized creature). 

 It's not a problem, because the rules for emanations override the general rules for AoE.

Quote from AntonSirius >>

You tell me to read the text of the spell, and then ignore half of it. Nice

 I ignored the part where you aren't casting it on an object, because I was talking about casting it on an object.

Quote from AntonSirius >>

But wait, you say, one's a Sphere and one's an Emanation. That changes its total AoE!

No, it doesn't. Or at least, it shouldn't

 I'm sympathetic to the claim that it shouldn't, but it absolutely does change the total AoE.

Quote from Thezzaruz >>

A easy example is to look at the Paladin aura's. The 5.5E Paladin says "in a 10-foot Emanation that originates from you" while the 5E Paladin says "within 10 feet of you". The area that is covered by the aura really shouldn't differ between the editions but for that to be true then a 10-foot emanation cannot cover the same space as a 10-foot sphere. A 10-foot sphere should have a diameter of 20 feet but a 10-foot emanation should have a diameter of 25 feet (

Why "should" it have a 25-foot diameter?

A 10-foot radius from a corner of the paladin's square is still plenty of coverage, even if it wouldn't look nicely centered on Roll20. And if you want to ignore the DMG and put the point of origin in the center of the paladin's square, then the "If an area of effect covers at least half a square or hex, the entire square or hex is affected." language would still be applicable

Quote from sabin76 >>

So, by RAW, if a Large creature has an emanation of 10ft., it would affect nothing other than the creature (if it chooses)? And you think that's intended?

Might want to try that one again. A 10-foot Emanation covers a Large creature with room to spare

Quote from AntonSirius >>

Why "should" it have a 25-foot diameter?

 Because "every point within 10' of the paladin" is a 25' diameter (or a 30' diameter, if you have a Large paladin for some reason).

Quote from MaximusArael020 >>

One thing that's interesting from the text that you quoted is that it says "An area of affect has a point of origin...", but then for the DMG "playing on a grid" section, it says "IF the area has a point of origin...". If all areas of effect have a point of origin, it shouldn't say "if", because it's just talking about areas of effect. 

Interestingly, all the glossary descriptions of the area of effect shapes (cube, sphere, cylinder, etc) state explicitly that they have a "point of origin", EXCEPT the one for emanation, which says it "extends in straight lines from a creature or object."

I'm not saying I agree with either interpretation (the rope thing seems unintentional) but the wording choice is interesting.

Not all "areas" are defined as AoEs though. You could have some environmental hazard which needs to be mapped onto the grid to determine who's affected, but isn't an Area of Effect as defined in the rules 

To me, the rope hypothetical should be an obvious reductio ad absurdum to show why that interpretation is actually incorrect

Quote from jl8e >>

 It's not a problem, because the rules for emanations override the general rules for AoE.

And where in the rules does it indicate that exception?

Quote from AntonSirius >>

And where in the rules does it indicate that exception?

Emanation says it extends from a creature or object. A creature or object is not a point. 

Quote from AntonSirius >>

Quote from jl8e >>

 It's not a problem, because the rules for emanations override the general rules for AoE.

 

And where in the rules does it indicate that exception?

 It does so by existing. 

Specific beats general does not mean "only if the rule says it overrides". It means that if a specific rule says X, it beats the general rule that says Q. The definition of emanation specifies that it extends from a non-point, so it does. 

Vast amounts of the D&D rules function this way.

Quote from AntonSirius >>

Why "should" it have a 25-foot diameter?

Because that's how effects like aura's or spells like Spirit Guardians and similar things are expected to work. They extend from you out to a specified range, not from a point slightly besides you. It's how they worked in 5E and it's how they work in pretty much any fantasy setting out there. And this matches well with what the rules for Emanations say too. You just have to accept that they aren't really an AoE effect and thus work somewhat differently that other AoE's.

As I said above, they screwed up. Emanations have little in common with other AoE's (except from covering an area) and they really shouldn't have been called one without also being clearly called out as being different. I understand why they did it because the old "within X from you" or "around you" language used in 5E for moving AoE's wasn't defined enough as a concept, they just didn't get it all the way right.

Quote from AntonSirius >>

To me, the rope hypothetical should be an obvious reductio ad absurdum to show why that interpretation is actually incorrect

I'd have to disagree. The rope issue doesn't mean that there is anything wrong with emanations, it just means that Emanation wasn't a good fit for that effect of the Darkness spell. In 5E the Darkness spell used language along the lines of 15-foot sphere from point on the object instead and that would have worked well in 5.5E too as that would have given you one single sphere instead of 50 ft of spheres.

Again I understand why they made the change as emanations is the concept they chose for moving AoE's, they just didn't think it through

Quote from sabin76 >>

So, by RAW, if a Large creature has an emanation of 10ft., it would affect nothing other than the creature (if it chooses)? And you think that's intended?

In fact, I think we have a bit of specific vs general here. AoE rules do, indeed, say that all AoEs have a "point of origin", but then it goes on to say that each type describes that point. Well, only one of those types doesn't describe a point of origin: the emanation. It describes the creature or object as the source.

 I agree with this simple explanation, and the observation made by MaximusArael and others in the thread.

A Sphere extends in straight lines from a point of origin outward in all directions, and an Emanation extends from the edge of its origin (e.g. a creature) instead of from a point in space.

The DMG says:

An area of effect must be translated onto squares or hexes to determine which potential targets are in the area. If the area has a point of origin, choose an intersection of squares or hexes to be the point of origin, then follow its rules as normal. If an area of effect covers at least half a square or hex, the entire square or hex is affected.

So even if you want to choose an intersection of squares, you must follow the Emanation rules ("extends in straight lines from a creature or an object in all directions"). When playing on a grid, a creature occupies the entire square, and the range is calculated from the edge of its tile outward:

Something like this for the Aura of Protection example: