D&D 5E Radius AoE also on walls?

Rya.Reisender · Mar 8, 2017

So I've been having lots of target and AoE discussions with my players lately and most of them I could answer, but about one thing I wasn't 100% sure and wanted to get some other opinions.

Let's take the spell "Spike Growth", it just refers to "ground" and "radius". My druid was arguing that the spikes should also grow at the cliffs within that 20 feet radius because cliffs are also "ground". But I feel like if it says "radius" and not "cylinder" it would never have any height. What do you think?

Sorcerers Apprentice · Mar 8, 2017

Spell effects with sizes listed as a radius are generally spheres. Is a cliffside inside such a sphere "ground"? That's entirely up to the DM, "ground" is not a concept in the D&D rules.

I'd probably say yes, if only to avoid having to decide at exactly what angle ground stops being ground.

Imaculata · Mar 8, 2017

Spike Growth

2nd-level transmutation

Casting Time: 1 action
Range: 150 feet
Components: V, S, M (seven sharp thorns or seven small twigs, each sharpened to a point)
Duration: Concentration, up to 10 minutes

The ground in a 20-foot radius centered on a point within range twists and sprouts hard spikes and thorns. The area becomes difficult terrain for the duration. When a creature moves into or within the area, it takes 2d4 piercing damage for every 5 feet it travels. The transformation of the ground is camouflaged to look natural. Any creature that can’t see the area at the time the spell is cast must make a Wisdom (Perception) check against your spell save DC to recognize the terrain as hazardous before entering it.

It says a 20-foot radius on the ground. So in my view that's not a sphere, it's a disc. But the question is, can it extend up or down a wall? In my view this depends on the type of surface. "Ground" in this case, refers to a surface that thorns could logically sprout from. So the surface would need to be some form of soil. If the wall is solid rock, but the DM rules that plants can grow from it, then yes, that makes that ground as well. So I would curve the disc up or down a bit. For the sake of convenience, lets say the spell covers 10 ft. on the ground, and another 10 ft. on the cliff. I would allow the spell to continue a further 10ft. up or down that cliff.

Likewise, if the Druid was to cast this spell directly at a 90 degree angle on the side of a cliff, I would allow it. There's nothing in the spell that says the radius needs to be completely horizontal. Rule of cool applies here. If using this spell this way makes the spell more fun, and if it seems to make sense, then I would allow it. I would approach the way in which these sort of spells are placed similar to the way players can place and AOE effect in Guild Wars 2. The AOE circle aligns with the terrain the spell is cast on.

aco175 · Mar 8, 2017

Is there some kind of advantage the player is looking for by having the spikes grow up the wall? I cannot think of any advantage, maybe trying to climb the wall or pushing someone into the wall. I would most likely allow it myself.

CydKnight · Mar 8, 2017

Imaculata said:
It says a 20-foot radius on the ground. So in my view that's not a sphere, it's a disc. But the question is, can it extend up or down a wall? In my view this depends on the type of surface. "Ground" in this case, refers to a surface that thorns could logically sprout from. So the surface would need to be some form of soil. If the wall is solid rock, but the DM rules that plants can grow from it, then yes, that makes that ground as well. So I would curve the disc up or down a bit. For the sake of convenience, lets say the spell covers 10 ft. on the ground, and another 10 ft. on the cliff. I would allow the spell to continue a further 10ft. up or down that cliff.

Likewise, if the Druid was to cast this spell directly at a 90 degree angle on the side of a cliff, I would allow it. There's nothing in the spell that says the radius needs to be completely horizontal. Rule of cool applies here. If using this spell this way makes the spell more fun, and if it seems to make sense, then I would allow it. I would approach the way in which these sort of spells are placed similar to the way players can place and AOE effect in Guild Wars 2. The AOE circle aligns with the terrain the spell is cast on.

View attachment 81826

I have actually seen vines grown on hard surfaces like brick and concrete and even certain rock formations but it's usually something porous. I would probably have no problem allowing the growth on the rocky wall unless it was known to be something hard like granite or marble.

CydKnight · Mar 8, 2017

aco175 said:
Is there some kind of advantage the player is looking for by having the spikes grow up the wall? I cannot think of any advantage, maybe trying to climb the wall or pushing someone into the wall. I would most likely allow it myself.

Keeping a Giant Spider, or some other creature able to scale walls, from descending or ascending the wall to gain an advantage in combat? Or perhaps a creature that is able to scale walls they ended their last turn on the wall?

Dausuul · Mar 8, 2017

I would rule that a cliff face does not constitute "ground," though ledges on the cliff face might. As for determining the cutoff point, I'd go with something along the lines of "If you can traverse it without a climb speed or an Athletics check, it's ground."

Rya.Reisender · Mar 8, 2017

The current situation was that the Druid PC cast Spike Growth at the bottom of a cliff and then another PC knocked the enemy down into it. So in order to not take damage from the spikes, I wanted to be clever and make the enemy climb alongside the cliff wall rather than walk on the spikes. Then the Druid PC argued that the cliff walls should also have spikes and hurt.

Blue · Mar 8, 2017

I don't think there is a definitive answer. Both "ground" and "radius" (as in is it a disk or a sphere) are not defined.

In most spells, radius is referring to a sphere, so that would be my default. But with "ground" I can read that they are intending a disk.

Now, it has come up in play at my table, and effectively we made it a disk but one that could bend and cover walls. So if it was cast right at the base of the wall it would have a 20'r half circle on the ground and another 20'r half circle on the wall. Didn't cover any additional squares, just wasn't limited to being only horizontal. I'm not saying that's the "one true" interpretation, just what we did and it satisfied both player (prevented foes escape climbing up the wall) and the DM (same amount of squares covered, no power creep).

cmad1977 · Mar 8, 2017

To me this isn't a 'hill to die on' unless it changes something fundamental about the world.

I'd have said 'ok, cool. Spiky cliff hurts the bad guys some'

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D&D 5E Radius AoE also on walls?

Rya.Reisender

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Imaculata

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aco175

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CydKnight

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Dausuul

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Rya.Reisender

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