It came up in the last game about Courageous Anthem1.

Player Core page 428 states that:

When you’re playing in encounter mode and using a grid, areas are measured in the same way as movement (page 420), but areas’ distances are never affected by difficult terrain. Standard or greater cover can apply against areas, but not lesser cover.

Bending around corners:

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Not bending around corners:

enter image description here

Line of Effect says you need an unbroken path, but that contradicts "areas are measured in the same way as movement", and make no sense for things that do not fly out in straight line like shrapnel. Noise Blast should not care about corners at all, and arguably Fireball neither. Courageous Anthem's predessessor (Inspire Courage) had a Verbal component, and as we know sound does bend around corners.

I know GMs could and should make individual calls, like Earthquake should not even be stopped by solid walls. But currently Foundry (our virtual tabletop) has the non-bendy version, and most GMs are just accepting it.
Is there some other support for the bendy behavior?

  1. I know it is a 60 foot emanation, but I did not want to draw that much. Pretend it is a 3 action Heal
  • 1
    \$\begingroup\$ I just realized by "areas are measured in the same way as movement" they probably only meant "count every second diagonal cell as 2", and even this does not mean bending. Which makes even less sense for Noise Blast, or Courageous Anthem \$\endgroup\$
    – András
    Commented Jul 8 at 20:24
  • \$\begingroup\$ I thought there was a spell that specifically goes around corners, but I was mistaking it with other editions (fireball, for example). \$\endgroup\$
    – goodguy5
    Commented Jul 9 at 14:05

1 Answer 1


Area effects do not go around corners. Here's why:

As you note, Line of Effect says that effects do not bend around walls or corners. This actually does make sense in real life, even for auditory effects, because sound waves do travel in a straight line. They just also have the ability to reflect off most surfaces (including other waves), which causes them to break apart (diffract) and scatter in new directions. This is what creates the appearance of sound waves "turning" around corners or even in midair (this video has some great examples). All these invisible interactions alter the waves ever so slightly; we just don't usually notice unless we're paying careful attention.

In-universe, the existence of Line of Effect means that these altered sound waves (or heat waves, light waves, or whatever underlying wave is carrying the magic effect) no longer carry the AOE's effect. So if you're standing around a corner from someone singing a Courageous Anthem, you'll still hear the underlying sound waves, but the natural deterioration and/or interference caused by bouncing, has disrupted the magic effect. Or to think about it another way, the sound waves you hear aren't the original magic-infused waves: they're new waves created by the original sound waves travelling through the air. Their point of origin isn't the singer, which is why the new waves don't have the singer's magic. (Wiki link for detailed physics.)

That said, Remember the First Rule: "...the rules exist for you to use to tell the stories you want to tell and share exciting adventures with your friends." If you want AOEs to bend, and your table agrees, go for it. Heck, I've sometimes allowed bendy AOEs in my games. But since it depends heavily on the map layout, the target's location relative to the corner, the type of effect, the way the effect is transmitted (sound, light, heat, etc), and so on; and since it's likely to stop play for a while to discuss, I only do it for particularly important / dramatic / otherwise critical moments. The rest of the time, I use Line of Effect.

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    \$\begingroup\$ In real life sound waves DO turn around the corners. See diffraction and Huygens–Fresnel principle for details. \$\endgroup\$
    – Mołot
    Commented Jul 9 at 6:44
  • \$\begingroup\$ @Mołot interesting, and I think most people understand that... but this is a question about how magic works, so real-world physics can inform choices re: the first rule for immersion, but might not worth be citing directly in an answer. \$\endgroup\$ Commented Jul 9 at 12:58
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    \$\begingroup\$ @Ifusaso'he-him' if real physics is used in the answer at all, it should be accurate. This answer says that sound waves travel in straight lines and don't bend around the corners. It is false, literally opposite to the truth. This part should be corrected or removed. \$\endgroup\$
    – Mołot
    Commented Jul 9 at 13:51
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    \$\begingroup\$ "They just also have the ability to reflect off most surfaces, creating the appearance of "turning" around corners. But a reflected sound wave is almost always altered or deteriorated as a result of colliding with a surface (this video has some great examples). We just don't usually notice these minor changes unless we're paying attention to them." Sounds close enough for the layman to me \$\endgroup\$ Commented Jul 9 at 23:20
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    \$\begingroup\$ @thatgirldm they indeed do make U turns on the edges. Diffraction is not bouncing. Huygens Fresnel Principle says they travel in spheres all the time and apparent straight lines are indeed only the effect of interference. Waves are weird. \$\endgroup\$
    – Mołot
    Commented Jul 10 at 6:40

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