Just what exactly breaks line of effect for a burst?


Rules Questions

Dark Archive

So, I started a thread yesterday Blue Dragon: Desert Thirst Damage? where I asked about the effects Desert Thirst would have on creatures, if any.

The conclusion was that it has no effect on creatures.

One (or more) of three reasons were given, depending on who you ask:
1. It doesn't explicitly mention creatures, so it doesn't affect creatures, even if the rules text WAS phased in a way that part of a creature would be a valid target. The argument was that if the rules don't explicitly tell you something can happen, it can't. (I disagree with both the premise, and the results of the application of the premise to this particular situation, but to each their own).
2. It calls out unattended liquids, liquid based magic items, and liquid based items in a creature's possession as the types of valid target (and doesn't call out attended liquids that are not items), therefore bodily fluids are not a valid target, and neither is a pool that someone is swimming in.
3. Skin(and armor, etc) would break line of effect, thus making bodily fluids not a valid target:

Magic Rules wrote:
A burst spell affects whatever it catches in its area, including creatures that you can't see. It can't affect creatures with total cover from its point of origin (in other words, its effects don't extend around corners). The default shape for a burst effect is a sphere, but some burst spells are specifically described as cone-shaped. a burst's area defines how far from the point of origin the spell's effect extends.

So, there's a statement that it can't effect creatures with total cover from the point of origin, and another that says its effects don't extend around corners. I'm going to take those two statements and use them to infer that it also doesn't affect objects with full cover from the Point of Origin.

Now, in this case, it's obvious that it's supposed to affect potions in glass containers since they're explicitly called out, however, the glass should be giving the potion full cover, so why exactly would it effect potions?

1. Does glass not block line of effect?
2. Is line of effect only blocked if the obstruction is a certain thickness? If so, what thickness is that?
3. If line of effect somehow not relevant if you are pressed up against the obstruction?
4. What if the potions are stored in your backpack? Are they still a valid target? How about a box in a backpack?
5. How about a chest?
6. How about a chest built into a wall?
7. What if the potions are unattended?
8. Unattended behind a sheet of parchment, or inside a glass Jug.

In short:
For the purpose of Line of Effect, what is the important distinction, and where is the line drawn between "Behind a Stone Wall" and "Inside a Glass Vial"?

I'm interested in hearing any points or arguments anyone has for these questions.


Darkholme wrote:
The argument was that if the rules don't explicitly tell you something can happen, it can't. (I disagree with both the premise, and the results of the application of the premise to this particular situation, but to each their own).

That's the stance of the devs themselves, as far as I know. Someone around here probably has the quote(s) somewhere.


Line of Effect
To determine line of effect, pick any corner of your space and trace a line from that corner to every corner of the target's space. If at least one line doesn't pass through or touch blocking terrain, then you have line of effect.

Read more: http://www.enworld.org/forum/showthread.php?306415-Understanding-Line-of-Si ght-and-Line-of-Effect&s=e4000ac61d8b3fe102487200407b0f4a#ixzz3C7gWX2JG

Blocking Terrain
A type of terrain that blocks squares, often by filling them. Blocking terrain provides cover, interferes with movement around it, and blocks line of effect. It also blocks line of sight, unless it’s transparent.

Read more: http://www.enworld.org/forum/showthread.php?306415-Understanding-Line-of-Si ght-and-Line-of-Effect&s=e4000ac61d8b3fe102487200407b0f4a#ixzz3C7gfV9vS

From these I would say, if it were hanging on your belt and they shot the ability off at you, from the opposite side of where it's hanging, it's fine. If you and it are facing each other, and it's hanging by your belt in the back, I'd say it's protected, anywhere else, and I'd say it's f~@@ed.

Shadow Lodge Contributor, RPG Superstar 2010 Top 8

Clearly, the potion bottle is just a specialized form of armor the potion is wearing, and thus does not break line of effect (anymore than wearing full plate renders you immune to magic))

Asked and answered, next? :)

Scarab Sages

There's no facing in PF, so you can't claim to have been looking the other way, and therefore your potions got sheltered.

If players are going to benefit from the assumption that they're forever spinning on the spots like tops, and able to see in all directions simultaneously, then they should have to accept the rough with the smooth.

The real reason the dragon's ability doesn't work on bodily fluids, has nothing to do with line of effect. It's because the game writers don't want it to do so, as it would turn a minor treasure-screwing ability into horrid wilting.

Dark Archive

@The Indescribable:
So here is what I take away from that. Let me know if any of this seems incorrect:

1: Line of effect is based on being able to draw at least 1 straight line from a corner of your square to a corner of the square of the target that does not pass through blocking terrain.
1a) It doesn't matter if there is something in the way of the target itself, only if there is something in the way of a square it occupies.
2: Blocking terrain blocks /*squares*/ not the target.
2a) Creatures provide cover and you cannot move through their squares, therefore creatures count as blocking terrain.
2b) Because of 1a, In the case of a rat in a steel box in the middle of a 5 foot square, you have line of effect to the rat, it's not protected.
2c) Because of 2a, In the case of a rat, without a steel box on the other side of a doorway, with a creature standing in the doorway, you do not have line of effect to the rat, and it is protected.
2d) RAW, it doesn't matter if you are in the way of a direct line to the target, so long as it is still inside a square they can target (IE your square, as a medium creature) then they have line of effect on it.

Dark Archive

DominusMegadeus wrote:
Darkholme wrote:
The argument was that if the rules don't explicitly tell you something can happen, it can't. (I disagree with both the premise, and the results of the application of the premise to this particular situation, but to each their own).
That's the stance of the devs themselves, as far as I know. Someone around here probably has the quote(s) somewhere.

If there is a quote to that effect somewhere that someone can point me to, that would be both good to know, and a disheartening thing to learn which would take some of the magic out of the game for me.

Snorter wrote:

There's no facing in PF, so you can't claim to have been looking the other way, and therefore your potions got sheltered.

If players are going to benefit from the assumption that they're forever spinning on the spots like tops, and able to see in all directions simultaneously, then they should have to accept the rough with the smooth.

I agree with you. I would actually prefer if the rules had facing built in and the game was designed to handle that, but that is clearly not the case.

DominusMegadeus wrote:
The real reason the dragon's ability doesn't work on bodily fluids, has nothing to do with line of effect. It's because the game writers don't want it to do so, as it would turn a minor treasure-screwing ability into horrid wilting.

This point is irrelevant to this thread, which is why I tried to link and sum up what led me to my question in the initial post rather than simply continue in the other thread (this thread is about how line of effect works, not about the ability Blue Dragons have). I would rather not have to repeat everything I or other people said in the other thread in detail. If that is what you would like to discuss, feel free to hop threads, read the discussion there, and if you have anything to add, then do so.


The dragon's ability works on potions because that is what it is designed to do, and the ability says that it does it. It ignores the vial glass just like finger of death ignores your armor or any other spell ignores your armor.

It it would be just like a spell that said it destroyed any arrows in your possession. Even if they are in a backpack or a quiver with a top to it the spell would work. Now of course Paizo could go on and make a long list of exceptions and break down why the spell works, but they are going to assume that you take the effect at face value, and won't parse the rules to say "Your ability is not functional Paizo".

Yes, I am also saying that by RAW such an ability may not work if they don't specifically call out every rules exception it needs in order to work. However in order to save space in the book they are not going to do that.


The devs have also said an ability can only do what the rules say it can do. That is why it won't affect people.

PS:DominusMegadeus was correct. That is the answer. If you want a strictly rule(book) based one that fits perfectly within the book, the "the devs have said so" may be the best answer you get.


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SKR wrote:


As it turns out, we often don't call out the general rule when we make a specific rule that breaks the general rule. For example, the Cleave feat never states, "although you can normally only make one attack with a standard action, when using Cleave you can..."

That is to show they won't explain everything in detail every time.

As for "you only get what the rules give you" I will try to find it later.

Liberty's Edge

PRD wrote:

Cover

To determine whether your target has cover from your ranged attack, choose a corner of your square. If any line from this corner to any corner of the target's square passes through a square or border that blocks line of effect or provides cover, or through a square occupied by a creature, the target has cover (+4 to AC).

When making a melee attack against an adjacent target, your target has cover if any line from any corner of your square to the target's square goes through a wall (including a low wall). When making a melee attack against a target that isn't adjacent to you (such as with a reach weapon), use the rules for determining cover from ranged attacks.

Low Obstacles and Cover: A low obstacle (such as a wall no higher than half your height) provides cover, but only to creatures within 30 feet (6 squares) of it. The attacker can ignore the cover if he's closer to the obstacle than his target.

Cover and Attacks of Opportunity: You can't execute an attack of opportunity against an opponent with cover relative to you.

Cover and Reflex Saves: Cover grants you a +2 bonus on Reflex saves against attacks that originate or burst out from a point on the other side of the cover from you. Note that spread effects can extend around corners and thus negate this cover bonus.

Cover and Stealth Checks: You can use cover to make a Stealth check. Without cover, you usually need concealment (see below) to make a Stealth check.

Soft Cover: Creatures, even your enemies, can provide you with cover against ranged attacks, giving you a +4 bonus to AC. However, such soft cover provides no bonus on Reflex saves, nor does soft cover allow you to make a Stealth check.

Big Creatures and Cover: Any creature with a space larger than 5 feet (1 square) determines cover against melee attacks slightly differently than smaller creatures do. Such a creature can choose any square that it occupies to determine if an opponent has cover against its melee attacks. Similarly, when making a melee attack against such a creature, you can pick any of the squares it occupies to determine if it has cover against you.

Partial Cover: If a creature has cover, but more than half the creature is visible, its cover bonus is reduced to a +2 to AC and a +1 bonus on Reflex saving throws. This partial cover is subject to the GM's discretion.

Total Cover: If you don't have line of effect to your target (that is, you cannot draw any line from your square to your target's square without crossing a solid barrier), he is considered to have total cover from you. You can't make an attack against a target that has total cover.

Improved Cover: In some cases, such as attacking a target hiding behind an arrowslit, cover may provide a greater bonus to AC and Reflex saves. In such situations, the normal cover bonuses to AC and Reflex saves can be doubled (to +8 and +4, respectively). A creature with this improved cover effectively gains improved evasion against any attack to which the Reflex save bonus applies. Furthermore, improved cover provides a +10 bonus on Stealth checks.

PRD wrote:


Line of Effect: A line of effect is a straight, unblocked path that indicates what a spell can affect. A line of effect is canceled by a solid barrier. It's like line of sight for ranged weapons, except that it's not blocked by fog, darkness, and other factors that limit normal sight.

You must have a clear line of effect to any target that you cast a spell on or to any space in which you wish to create an effect. You must have a clear line of effect to the point of origin of any spell you cast.

A burst, cone, cylinder, or emanation spell affects only an area, creature, or object to which it has line of effect from its origin (a spherical burst's center point, a cone-shaped burst's starting point, a cylinder's circle, or an emanation's point of origin).

An otherwise solid barrier with a hole of at least 1 square foot through it does not block a spell's line of effect. Such an opening means that the 5-foot length of wall containing the hole is no longer considered a barrier for purposes of a spell's line of effect.

You should use both rules to see if a item is protected against an effect or attack.

Darkholme wrote:

@The Indescribable:

So here is what I take away from that. Let me know if any of this seems incorrect:

1: Line of effect is based on being able to draw at least 1 straight line from a corner of your square to a corner of the square of the target that does not pass through blocking terrain.

True but incomplete.

Darkholme wrote:


1a) It doesn't matter if there is something in the way of the target itself, only if there is something in the way of a square it occupies.

False. "You must have a clear line of effect to any target that you cast a spell on or to any space in which you wish to create an effect."

and "A line of effect is canceled by a solid barrier."
So if there is something in the way and it is not part of the target it block line of effect (LoE for short)

Darkholme wrote:


2: Blocking terrain blocks /*squares*/ not the target.

It depend. Some terrain or item can block Loe to a target but not the whole square.

Darkholme wrote:


2a) Creatures provide cover and you cannot move through their squares, therefore creatures count as blocking terrain.

Imprecise. Creature provide soft cover and that isn't enough to block LoE.

Darkholme wrote:


2b) Because of 1a, In the case of a rat in a steel box in the middle of a 5 foot square, you have line of effect to the rat, it's not protected.

No. You have LoE to the square and the box, but the LoE to the rat is blocked by a solid barrier.

Darkholme wrote:


2c) Because of 2a, In the case of a rat, without a steel box on the other side of a doorway, with a creature standing in the doorway, you do not have line of effect to the rat, and it is protected.

No, soft cover is insufficient to block LoE.

Darkholme wrote:


2d) RAW, it doesn't matter if you are in the way of a direct line to the target, so long as it is still inside a square they can target (IE your square, as a medium creature) then they have line of effect on it.

If with "you" you mean a creature, barring some exception that should be adjudicated by the GM (like a kaiju sitting between you and the target), creatures only provide soft cover.

- * -

While I don't think that it is written anywhere, containers and their content or people and their clothing count as a single target, so if you can target the container you can target the content.

There are exceptions that require GM adjudication or the use of common sense.

The content of a backpack generally can't be targeted simply because you can target the backpack. Same thing for a sack or any other container containing several different items. Same thing for targeting a room or a box with people in it. The basic assumption is that you can target target a container and its content at the same time only if they work as a single unit: water and waterskin, vial and potion, beef can and the Spam in it and so on.

A tower shield give total cover to the guy using it in the right conditions, but normally it only give a bonus to AC, and it never block LoE to other people (barring special abilities that change that rule).

- * -

Typing with a young lady cat walking on the keyboard is hard and slow work, so maybe I have missed something. I will reread this piece alter and eventually add another post.

Dark Archive

Alright Diego, I think that makes Line of Effect much more clear.

Just to verify I understand how the containers part works:
Potion & Vial: 1 Target.
Coinpurse & Coins inside: 1 Target.
Spell Component Pouch and Spell Components: 1 Target.
Backpack and its Contents: Backpack is valid, contents are protected.
Chest Full of Treasure: Chest is valid, treasure is protected.
Arrows and Quiver: Quiver is valid, arrows are valid unless using a quiver designed to block LOE.
Character and an object they swallowed (like a ring): The character is valid, the objet is protected.

Liberty's Edge

Yes, I would rule that way in all the situations you have depicted.

Darkholme wrote:
Snorter wrote:

There's no facing in PF, so you can't claim to have been looking the other way, and therefore your potions got sheltered.

If players are going to benefit from the assumption that they're forever spinning on the spots like tops, and able to see in all directions simultaneously, then they should have to accept the rough with the smooth.

I agree with you. I would actually prefer if the rules had facing built in and the game was designed to handle that, but that is clearly not the case.

1st and 2nd edition of AD&D had facing rules, D&D 3.0 had facing rules.

They were removed because some people think that they are too complicated or slow gameplay and because a square grid don't work so well with facing rules, an hexagonal one work better.
I think that with a bit of work it is possible to adapt the 3.0 rules about facing to Pathfinder, the only question is if it is worth the hassle and if it can break some rule or class ability.

If you are willing to homerule some thing it is feasible.

Dark Archive

Diego Rossi wrote:

1st and 2nd edition of AD&D had facing rules, D&D 3.0 had facing rules.

They were removed because some people think that they are too complicated or slow gameplay and because a square grid don't work so well with facing rules, an hexagonal one work better.
I think that with a bit of work it is possible to adapt the 3.0 rules about facing to Pathfinder, the only question is if it is worth the hassle and if it can break some rule or class ability.

If you are willing to homerule some thing it is feasible.

Hmm. I may look into the 3e facing rules and consider putting them into my home games. I totally forgot about that. I haven't looked at my 3.0 PHB since like 2006 (it was quite a while after its release before we had a 3.5 PHB at the table; we mostly continued to use the 3.0 PHB, with printed out 3.5 SRD base class writeups - I remember buying lots of other books, but I never had much cause to update the PHB - I was pretty happy with it at the time. I eventually upgraded because my 3.0 PHB was falling apart).

Scarab Sages

Snorter wrote:
The real reason the dragon's ability doesn't work on bodily fluids, has nothing to do with line of effect. It's because the game writers don't want it to do so, as it would turn a minor treasure-screwing ability into horrid wilting.
Darkholme wrote:
This point is irrelevant to this thread, which is why I tried to link and sum up what led me to my question in the initial post rather than simply continue in the other thread (this thread is about how line of effect works, not about the ability Blue Dragons have). I would rather not have to repeat everything I or other people said in the other thread in detail. If that is what you would like to discuss, feel free to hop threads, read the discussion there, and if you have anything to add, then do so.

That's OK. I wasn't trying to be snarky at all.

I thought that specific point needed addressing.

I read the first post which implied that someone had been arguing that the potion owner wasn't affected because 'armor blocks the effect'.

And that that had led other people to argue that all bursts can be blocked by intervening creatures, containers, or armor.

I was pointing out that the dragon's ability doesn't affect creatures at all, so it can't be used to prove that armor, in itself, provides cover to block line of effect. For this, or any other spell/SLA/supernatural ability.

Dark Archive

Snorter wrote:
Snorter wrote:
The real reason the dragon's ability doesn't work on bodily fluids, has nothing to do with line of effect. It's because the game writers don't want it to do so, as it would turn a minor treasure-screwing ability into horrid wilting.
Darkholme wrote:
This point is irrelevant to this thread, which is why I tried to link and sum up what led me to my question in the initial post rather than simply continue in the other thread (this thread is about how line of effect works, not about the ability Blue Dragons have). I would rather not have to repeat everything I or other people said in the other thread in detail. If that is what you would like to discuss, feel free to hop threads, read the discussion there, and if you have anything to add, then do so.

That's OK. I wasn't trying to be snarky at all.

I thought that specific point needed addressing.

I read the first post which implied that someone had been arguing that the potion owner wasn't affected because 'armor blocks the effect'.

And that that had led other people to argue that all bursts can be blocked by intervening creatures, containers, or armor.

I was pointing out that the dragon's ability doesn't affect creatures at all, so it can't be used to prove that armor, in itself, provides cover to block line of effect. For this, or any other spell/SLA/supernatural ability.

Ah. Okay. Fair enough.

Yeah, it doesn't affect creatures, but in the other thread someone also mentioned that an additional reason it cannot affect creatures is that the creature's skin and armor would provide cover to their bodily fluids (and from what I have gathered in this thread, that particular point isn't actually correct, since the skin and armor would be treated the same as a container for a potion, and the bodily fluids of a creature are part of a creature, therefore, the creature's outsides do not block line of effect for the creature's insides (but foreign objects inside the creature would have line of effect blocked)).

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