# Area of Effect spells centered on the caster

### Rules Questions

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Yar!

The magic section states that "The point of origin of a spell is always a grid intersection."

However, many spells specify that it's effects are "centered on you".

Only Large, Gargantuan and Colossal creatures have a center that is on a grid intersection. Huge, Medium, and smaller creatures are centered on a square.

How are these "centered on you" spells supposed to work? How do you do it?

...

For example: when you have a 20' radius emanation centered on you and you are a medium sized creature, do you:

A: choose a corner of your square for the center of the effect, thus making you off-center... the spell is not actually centered on you despite what the spell description says.

B: count 20' (4 squares) out from your square in each direction, thus making the spell a 22.5' radius effect, but it is actually centered on you.

C: as B, but the last square in the "sphere" is only half covered by the spells effect, thus the spell is centered on you, and it is a proper 20' radius, but...

c1: creatures in the half-affected squares still take the full effects of the spell.

c2: creatures in the half-affected squares take only partial effects / gain a bonus to resist the effects.

D: something else.

...

~P

I've seen both (a) and (b), with the real sticklers tending towards (a).

hogarth wrote:
I've seen both (a) and (b), with the real sticklers tending towards (a).

I'm in the A and B camp as well. Depends on the effect and how important it is to be very precise.

For example, Zone of Silence is a 5' radius emanation centered on you. I would have that affect every square around the caster.

That is, it would affect:

ooo
oCo
ooo

It would be strange if it only worked like this:

oo-
oC-
---

Yar.

FarmerBob wrote:

For example, Zone of Silence is a 5' radius emanation centered on you. I would have that affect every square around the caster.

That is, it would affect:

ooo
oCo
ooo

It would be strange if it only worked like this:

oo-
oC-
---

Indeed.

Being as this is the internets though, I feel the need to add this affirmation:

Quote:

ooo
oCo
ooo

is a (b) interpretation, while

Quote:

oo-
oC-
---

is an (a) interpretation.

o_O

~P

I'd say A for targeted spells (like fireball) that you just happen to be casting on yourself, B for all spells which are specifically centered on you.

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Has there been a definitive answer on this?

Here is how I look at it. The basic rule is that "The point of origin of a spell is always a grid intersection." However, some spells specifically say that "centered on you" or "centered on the caster." In that case, I would read it to mean that the general statement "...always a grid intersection..." yields to a more specific context (a given spell or effect that centers the effect on the caster.) That's how I run it.

But, I was hoping to see if there was something more official.

Mark

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Not really. RAW is strictly on the side of grid intersections per the rules for emanation/burst spells. SKR (I think; can't find the thread now) went by the grid intersection rule when discussing a dragon casting antimagic shell--the shell only covered a small portion of the dragon (the area around a grid intersection of the dragon's choice).

However, I find this cumbersome and rule differently in my games. Spells that emanate from the caster should act like other abilities that emanate from the user (such as a paladin's aura and a cleric's channel energy) to keep the rules simple. The idea that, e.g., channeling energy or globe of invulnerability is "centered" on the user but asymmetric around said user is patently absurd. So for me, if an area effect is specified as being centered on a creature, the square is the center, and the radius begins at the creature's boundaries.

blahpers wrote:

Not really. RAW is strictly on the side of grid intersections per the rules for emanation/burst spells. SKR (I think; can't find the thread now) went by the grid intersection rule when discussing a dragon casting antimagic shell--the shell only covered a small portion of the dragon (the area around a grid intersection of the dragon's choice).

However, I find this cumbersome and rule differently in my games. Spells that emanate from the caster should act like other abilities that emanate from the user (such as a paladin's aura and a cleric's channel energy) to keep the rules simple. The idea that, e.g., channeling energy or globe of invulnerability is "centered" on the user but asymmetric around said user is patently absurd. So for me, if an area effect is specified as being centered on a creature, the square is the center, and the radius begins at the creature's boundaries.

That is how I do it. My main character in PFS is a cleric, so when he uses channeling, well, this question comes up. For me, I think it's cleaner and makes more sense that if the effect is centered on the caster, then the caster is the center, not a corner of his or her space.

I wish there would be some sort of clarification, but the way I play it is the way I have seen others play it around here. It's not really a conflict, but the question does come up once in a while.

In 3.5 days, a) seemed to be well established. Yes, it creates some oddities. It's a necessary application if wanting consistency in how the combat and magic systems interact with the grid.

That said, PF developers have not been so slavish about the grid. The reach weapon diagonal situation comes to mind. How they might weigh in on this question, or how their input ends up being filtered through posters to this thread, then becomes uncertain for me.

I guess, in summary: people approach it in different ways. How an official answer might be worded is a coin toss.

This absolutely NEEDS clarification!
I've been running it like Blapher described because other ways lead to madness imo. If they rule differently the only time I will abide by it is if the GM I have insist upon it working like A or if I'm playing PFS.

Lifat wrote:

This absolutely NEEDS clarification!

I've been running it like Blapher described because other ways lead to madness imo. If they rule differently the only time I will abide by it is if the GM I have insist upon it working like A or if I'm playing PFS.

To be honest, when I run PFS, I run it like B. It's the only thing that makes sense to me. As I read it, it is an exception to the "always a grid intersection." A spell or effect which is centered on the caster is...centered...on the caster. Not on a corner, or not adjacent to the caster...CENTERED. To me, that's the only reading that makes sense. Either centered means centered, or it doesn't.

I don't think it's a game-breaker either way, honestly, but clarification would be nice.

Pathfinder, like 3.5, has grid-templates.

Splendor wrote:
Pathfinder, like 3.5, has grid-templates.

Correct, but those don't answer the question that I (and others) have asked.

A medium-sized creature, for example, doesn't occupy a grid intersection; he or she occupies a square. For some of the larger creatures, this isn't an issue, because their center-point IS a grid intersection, so it's not a problem. But, for creatures that occupy only one square, then the grid intersection rule doesn't make sense for a spell or effect that is "centered on the caster."

So I visited this thread having a creature that gives off a 5' radius effect or sorts and was wanting some continuity between magical and more physicalish effects. So by a grid idea, if you gave off a 5' radius effect it would just skim into half of the areas around you-do you give them a save with a bonus? Ignore it? Partial damage, etc.? See how poorly that works? This versus area of effect "creature only" which would not go into a any adjoining area. Why as a defense mechanism would a creature have a 5' area of effect on something? Just for when it is grappling? To fry bugs crawling on it? More like it is meant to blast whatever is around it. Ruling=one square on any side.

So along these lines I come to this thought. While the mechanics of magic are endlessly entertaining to me, I must say that the idea that some infinitely small emanation point within a creature is the origin of the magical effect is less coherent than that the energy field of the creature as it were is the focus and origin. Thus, it would be 5' etc. OUTSIDE of the area the creature takes up....referring to the anti magic sphere idea and the dragon is the clincher or some similar example. Hmm...maybe that wasn't this thread. Why it was not worded just with the simple "excepting the area the (caster, etc.) takes up" is beyond me but that is what happens when mortals try to interpret THE AWE INSPIRING MAJESTY OF MYSTRA! I'm betting THE AWE INSPIRING POWER OF THE TYPESETTER AND GRAPHIC DESIGNER is what ruled here, and they were either really stoned that day or there was an ongoing battle between game designers and it ended up with seemingly conflicting way of interpreting game mechanics with that (lazy, but pacifying) old chestnut "let the GM rule on it" as the excuse not to clean it up. Wisely, Pathfinder has not been hardcore about freaking out fanatics to the grid, so to speak, while the rest of us do what seems more obvious as is usual. Have that be your ruling, and your Occam's Razor of sorts....the philosophical concept that is, not the artifact...heh....

Look at the area covered in a 10ft radius centered on a grid intersection. It covers 12 squares total.

Now look at the area covered in a 10ft radius centered on a square (treated as reach because how else would you measure it?). It covers 21 squares.

Almost. Freaking. Double.

This question NEEDS an answer. The fact that it's been 4 years since it was asked and it has gone totally ignored is obscene.

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FAQ wrote:

Big creatures and centered effects: If a Large or larger creature has up an effect “centered on you,” does that mean that sometimes the emanation doesn’t even affect the creature’s entire space, let alone anything else?

Answer: No, when a creature uses an emanation or burst with the text “centered on you,” treat the creature’s entire space as the spell’s point of origin, and measure the spell’s area or effect from the edges of the creature’s space. For instance, an antimagic field cast by a great wyrm red dragon would extend 10 feet beyond her 30x30 foot space, for a total of a 50 foot diameter.

While the question only refers to big creatures, the response appears to address creatures of any size. IMHO, it makes perfect sense to fully apply this ruling to all creatures, and I will do so baring further official clarification.

I imagine the powers that be are intentionally waiting to see the reaction to this FAQ before possibly rewording it.

Byakko wrote:
FAQ wrote:

Big creatures and centered effects: If a Large or larger creature has up an effect “centered on you,” does that mean that sometimes the emanation doesn’t even affect the creature’s entire space, let alone anything else?

Answer: No, when a creature uses an emanation or burst with the text “centered on you,” treat the creature’s entire space as the spell’s point of origin, and measure the spell’s area or effect from the edges of the creature’s space. For instance, an antimagic field cast by a great wyrm red dragon would extend 10 feet beyond her 30x30 foot space, for a total of a 50 foot diameter.

While the question only refers to big creatures, the response appears to address creatures of any size. IMHO, it makes perfect sense to fully apply this ruling to all creatures, and I will do so baring further official clarification.

I imagine the powers that be are intentionally waiting to see the reaction to this FAQ before possibly rewording it.

The answer section in the FAQ doesn't specify what creature size the answer applies to. Therefore it is reasonable to treat that text as applying to all creatures regardless of size.

Snowblind wrote:
Byakko wrote:
FAQ wrote:

Big creatures and centered effects: If a Large or larger creature has up an effect “centered on you,” does that mean that sometimes the emanation doesn’t even affect the creature’s entire space, let alone anything else?

Answer: No, when a creature uses an emanation or burst with the text “centered on you,” treat the creature’s entire space as the spell’s point of origin, and measure the spell’s area or effect from the edges of the creature’s space. For instance, an antimagic field cast by a great wyrm red dragon would extend 10 feet beyond her 30x30 foot space, for a total of a 50 foot diameter.

While the question only refers to big creatures, the response appears to address creatures of any size. IMHO, it makes perfect sense to fully apply this ruling to all creatures, and I will do so baring further official clarification.

I imagine the powers that be are intentionally waiting to see the reaction to this FAQ before possibly rewording it.

The answer section in the FAQ doesn't specify what creature size the answer applies to. Therefore it is reasonable to treat that text as applying to all creatures regardless of size.

This has been clarified on the boards, with notice that the FAQ will be updated to be more clear that only large creatures should be affected.

Also see here where he explains that this is partially to make sure they aren't buffing EMF as it is already pretty strong.

Sorry to bring this back, but I'll be the GM in a game for the first time soon. As a VL for the Pathfinder Card Game and having loved the RPG for a long time, I'd like to start running PFS RPG scenarios if this game goes well. Therefore, I wanted to run the mechanics of the game as by-the-book as possible so I'd be ready for PFS since most of the games I've played in were ran a little loose with the rules.

When taking a really close look at the mechanics of the game, spells and other effects that are centered on a creature instead of targeting a flat area was one of the roughest things for me to wrap my head around and what brought me here. When something is centered on a creature, it seemed logical for it to branch out from the space of the creature. Having this only be the case for large or larger creatures just seems very strange. Particularly when looking at 5-ft.-radius effects, it just seems really bonkers to me for it to only effect three other spaces. So for a medium or smaller creature, such a spell effects 3 or 4 spaces. For a large creature, the same spell effects 12 or 16 spaces. Again, that seems kind of crazy to me. It makes me think pretty much all casters who have spells that function "centered on" them should always have themselves enlarged in combat to get the most out of their spells and that seems really wrong to me.

This also brings up more questions for me. If a caster has to pick one of their corners when they cast a "centered on you" spell to be their center, what happens when the spell isn't instantaneous? If this effect moves around with them, like Zone of Silence, who's to say what corner is their center each turn? If the character moves, can't they say they just shifted their body so that instead of their center being the upper-right corner, it is now their lower-left corner? What if they just want to shift their body to change their center without moving? What kind of action is that? It seems like it'd be pretty minor, so I'd think it should be a free action. Then, basically, on the character's turn he can effected all nine squares around him anyway, for non-instantaneous spells.

I run it centered on the caster, any other way just doesn't make sense.

It helps to remember that the world isn't actually divided into 5-foot squares.