Question about height of Entangle spell

[Scorponok]

This spell is quite powerful. 40 ft. radius, need a DC:20 STR check to break free, lasts minutes, and is long range to boot. What I'm wondering about is how high the grasses, weeds,bushes and trees grow. If a group of archers on horseback charge at a Druid, and she entangles them, I assume the horses have to make the reflex save but do the riders on top of the horses also have to make a save? What about a wizard that is flying 5 feet off the ground - do the weeds and bushes end up catching and holding him?

I've also heard the spell only works if there is already significant foliage in the area, such as grass or bushes, but in a castle with stone floors, it doesn't work. I'm now actually not sure where I heard this, as both the PHB and d20srd don't mention this at all. Has this just been a commonly used house rule?

Also, how do you go about countering this? I can think of enlarging so the people that are entangled gain STR to help with breaking free, or putting the whole area into some sort of fog cloud such as Obscuring Mist. I guess if you really want to get creative you could just have the entangled creatures lie down into the grass so they don't get shot full of arrows while stuck. I've heard of players trying to set it on fire, but I don't think most DMs would rule that they catch fire. They're live plants after all, and short of them being dry, those don't catch fire so easily.

[Venger]

This spell is quite powerful. 40 ft. radius, need a DC:20 STR check to break free, lasts minutes, and is long range to boot. What I'm wondering about is how high the grasses, weeds,bushes and trees grow. If a group of archers on horseback charge at a Druid, and she entangles them, I assume the horses have to make the reflex save but do the riders on top of the horses also have to make a save? What about a wizard that is flying 5 feet off the ground - do the weeds and bushes end up catching and holding him?

I've also heard the spell only works if there is already significant foliage in the area, such as grass or bushes, but in a castle with stone floors, it doesn't work. I'm now actually not sure where I heard this, as both the PHB and d20srd don't mention this at all. Has this just been a commonly used house rule?

Also, how do you go about countering this? I can think of enlarging so the people that are entangled gain STR to help with breaking free, or putting the whole area into some sort of fog cloud such as Obscuring Mist. I guess if you really want to get creative you could just have the entangled creatures lie down into the grass so they don't get shot full of arrows while stuck. I've heard of players trying to set it on fire, but I don't think most DMs would rule that they catch fire. They're live plants after all, and short of them being dry, those don't catch fire so easily.

if you ride through on horseback, you and the horse need to save. you're both in the affected area. flying is speshul, so the wizard is safe.

the area is "plants" (http://www.d20srd.org/srd/spells/entangle.htm) so there needs to be some plants for you to cast it.

like with any spell of its ilk such as grease, the best counter is to just not step over there. if you get caught in entangle's initial area, you're kind of screwed, but you can foil it with any teleportation magic, abrupt jaunt, or freedom of movement. obscuring mist/fog cloud/etc wouldn't do anything. RAW, you can't burn entangle away

[BowStreetRunner]

The first thing you need to look at more closely is the Area described in the spell.

"Area: PLANTS in a 40-ft.-radius SPREAD" (emphasis added) Those two words are significant. If there are no plants, there is no effect. So a castle with stone floors and no indoor plants would not be a useful place to cast this spell.

As for a Spread, "A spread spell spreads out like a BURST but can turn corners. You select the point of origin, and the spell spreads out a given distance in ALL DIRECTIONS." (again, emphasis added) Since it is based off of a burst, we look at that description which reads "The default shape for a burst effect is a SPHERE..." So the effect works on all plants in a 40 ft radius sphere. Take every 5 ft cube in that sphere and apply the effect to every plant in each cube.

So if a character is in one of these 5 ft spaces and there is a plant in the same space they are certainly going to be affected. The part that the DM has to figure out is if there is a space within the effect that has no plants but there are adjacent spaces that do have plants, how far can the plants reach. Plants outside the area won't be affected and plants inside the area shouldn't be allowed to reach outside of the area. However, if for instance the only plants are grasses on the ground the DM will need to decide how high up inside the sphere they can reach.

[Darrin]

For the most part, this boils down to the Area: line in the spell description:

Area: Plants in a 40-ft.-radius spread.

"Spread" is a defined term in the rules (PHB p. 175), and it does travel out from the point of origin in all directions, horizontal as well as vertical, but unlike bursts and emanations it can spread around corners. So the area of the spell does in fact resemble a 40'-radius "globe". However, that doesn't mean that vines and branches automatically envelope the entire volume of that globe. The Area: line mentions "Plants" rather than describing a geometric volume. This is common in PHB spells, as the designers sometimes got the differences between "Area:" and "Target:" confused.

For simplicity's sake, most DMs infer that the available plantlife in a square magically grows and extends enough to entangle any creatures that are currently occupying the same square. However, I believe the common interpretation is that these plants do not extend their reach beyond those initial squares. A creature flying through an entangle area could be well within the 40'-radius of the spell effect but also be 20' above any plant that could conceivably entangle them. However, if the flying creature flew next to a 40' tall tree or a stone wall covered with ivy, it would likely need to make a Ref save to avoid becoming entangled.

This assumes the spell is cast outdoors. Even if the battle map does not list vegetation, trees, or even the type of terrain, most DMs assume there is enough vegetable matter or underground roots present in each square that the full area of the spell, at least on the ground, can entangle creatures. For DMs that want to get persnickety or attempt to reign in an out-of-control Druidzilla, they can declare that there's not enough vegetation in certain areas to grab anything, or they could restrict the effect of the spell to just those squares on the map that actually have vegetation drawn on them. For these cases, the spell's last paragraph essentially gives the DM the ability to modify, restrict, or outright negate the effects of the spell: "Note: The DM may alter the effects of the spell somewhat, based on the nature of the entangling plants." This line is present in both the PHB and SRD, so if you're looking for the Nerfbat, that's it right there.

Some DMs don't allow this spell to work unless there is explicitly some type of vegetation present in the environment description or on the battlemat. In the interests of pedantry, the spell description doesn't say anything about *creating* plants out of thin air. That would be a conjuration spell, not a transmutation spell. So the argument there is the spell can only use whatever plants are currently present in the environment.

In these situations, there are a few work-arounds:

1) Cast spore field (Complete Scoundrel) before you cast entangle. Molds, spores, and fungus are considered plants by RAW. Wall of thorns should also work.

2) Throw some plants onto the battlefield, such as a box of brown mold (DMG p. 71), a spore flask (Savage Species p. 48), or green air brambles (Complete Scoundrel p. 118).

3) Bring along a friendly treant or another mobile plant creature that can fight alongside you.

4) Cast impeding stones instead (similar effect, same area, doesn't require plants). You just need a stone floor or natural ground, so this works inside castles, natural caverns, and inside most urban areas.

5) Find a better DM who doesn't have an axe to grind against Druidzillas.

As far as some of the specific examples that you bring up, such as someone riding a horse, or a creature flying through the area: are the entangling plants aggressive and "stretchy" enough to grab a rider off of a horse or snatch an eagle out of the air?

Unfortunately, that's all pretty much in "DM's Call" territory. The spell description isn't detailed enough to describe what happens in all situations, but the designers were cognizant enough of the gray areas that they did give the DM a call-out in this particular spell to step in and adjudicate.

[Psyren]

As others have said, the spell can theoretically go 40ft high, but in practice you need plants for it to act on in a given cube of that area. So if you cast it in on some mossy rocks, enemies flying 30ft. (or even 5+ft) above those rocks will be pretty safe, but if you cast it in a thick forest with a high canopy, there's a chance the branches and vines will start grabbing stuff that's in the air.