Control Water

[RSP]

Control Water, one of my favorite spells in the game, has the following wording:

“Until the spell ends, you control any freestanding water inside an area you choose that is a cube up to 100 feet on a side.”

So here’s my question, does that cube become the “area of effect” of the spell; or does it still only effect water in that area, with the cube as the effective “range” which you can manipulate the water?

In practice, would the entire 100’ cube pop of looked at with Detect Magic?

if you cast the spell, and choose the entire 100’ sided cube, can someone Dispel your casting simply by selecting an area within that cube, even if there’s no water being affected there?

I don’t think I’ve seen wording like this before, or thought of the spell this way, but it’s interesting. Either your transmutation spell, affecting a river flow, can be dispelled by someone who targets dry land up to 95’ away, who might not even know there’s a river there, much less that it’s flowing oddly; or you can part a 100’ cube of water, which can’t be Dispelled (because the affected water isn’t in the area of the spell).

The latter example makes me think the cube is the spell’s area, but that means the spell isn’t actually targeting the water, which seems counterintuitive, particularly since that’s what the spell is limited to controlling per its effects.

Thoughts?

[No brains]

I think the best answer for all your questions is that the 100ft cube is the amount of water you are capable of manipulating at a time. Think of it as your 'mage hand' working all of the water.

All of that 100 foot cube would detect for magic, if you are currently doing something to it. With a range of 300 feet, you can choose any contiguous 100 feet within that range to work with.

If someone casts dispel magic on the water you're manipulating, I think it would end the spell. It's like dispel 'bites' your 'mage hand'. If you aren't working any of the water within 300 feet of you, dispel magic can still work on you, but not the water.

The weirdest part of control water is attempting to reconcile it with normal physics. Moving 100 feet of water really ought to move all the water around it too, but then the spell becomes abusable by creating water effects beyond the range of the spell and potentially 'hiding' from dispellation. Am I to believe that if this spell is cast in a larger body of water, no effect leaves my 100 foot cube of magically manipulated water even if it should? That this spell won't turn a slightly larger moat into a continuous water slide, or that a still lake remains undisturbed outside of the spell's target area?

[RSP]

I think the best answer for all your questions is that the 100ft cube is the amount of water you are capable of manipulating at a time. Think of it as your 'mage hand' working all of the water.

That doesn’t work though as the spell specifies otherwise. If the cube is only the area of available water, you never could use the Redirect option the way it clearly states you can:

“You cause flowing water in the area to move in a direction you choose, even if the water has to flow over obstacles, up walls, or in other unlikely directions. The water in the area moves as you direct it, but once it moves beyond the spell's area, it resumes its flow based on the terrain conditions. The water continues to move in the direction you chose until the spell ends or you choose a different effect.”

Redirect Flow lets a river travel over the embankment or straight up a wall, over a bridge or building, whatever. If the area of the spell is only the preexisting river, you could never have it flow “up walls”, because you’d be out of the initially designated cube, per “but once it moves beyond the spell's area, it resumes its flow based on the terrain conditions.”

Likewise with the Flood option which specifies you can have dry land in the area of the cube:

“You cause the water level of all standing water in the area to rise by as much as 20 feet. If the area includes a shore, the flooding water spills over onto dry land.”

So I think it has to be otherwise that you establish the size of the total area, then can manipulate the water within, as able by the spell.

The weirdest part of control water is attempting to reconcile it with normal physics. Moving 100 feet of water really ought to move all the water around it too, but then the spell becomes abusable by creating water effects beyond the range of the spell and potentially 'hiding' from dispellation. Am I to believe that if this spell is cast in a larger body of water, no effect leaves my 100 foot cube of magically manipulated water even if it should? That this spell won't turn a slightly larger moat into a continuous water slide, or that a still lake remains undisturbed outside of the spell's target area?

The spell affects the area outside the cube. Same as above with the Flood option:

“You cause the water level of all standing water in the area to rise by as much as 20 feet. If the area includes a shore, the flooding water spills over onto dry land.”

Likewise with Redirect:

“The water in the area moves as you direct it, but once it moves beyond the spell's area, it resumes its flow based on the terrain conditions.”

In a past campaign, we used Control Water’s Redirect Flow to change a river’s course at the top of a mountain fortress. Once the river was going into the structure, even though it eventually left the 100’ cube of area, it continued down the interior of the structure, flooding it, because that’s how it would naturally flow based on the terrain it now was in.

Though it didn’t matter to the campaign, the regular river bed was empty while we were redirect the river for the 10 minutes of the spell as it was no longer being fed.

[Unoriginal]

The weirdest part of control water is attempting to reconcile it with normal physics.

DnD does not use normal physics, so there's nothing to reconcile the spell with here.

Am I to believe that if this spell is cast in a larger body of water, no effect leaves my 100 foot cube of magically manipulated water even if it should?

Exactly.

Could make for an awesome boss fight, too. With the boss starting the fight meditating in the water they control.

Worth noting that it goes both ways: you cast Control Water near the top of a waterfall, the water you control doesn't get carried out of your reach by the current, either, even though it "should".

[RSP]

Worth noting that it goes both ways: you cast Control Water near the top of a waterfall, the water you control doesn't get carried out of your reach by the current, either, even though it "should".

Kind of. Control Water has very limited functionality. There is no “water bending” feature of it. Depending on which effect you use, the water may or may not get carried out of your reach.

Flood seems to contain its effect to the cube (but expands outside the original water area), while Redirect Flow will continue outside the cube, but not in your control.

And just to clarify: I don’t think there’s an effect that stops water, so I’m not sure how you would stop a waterfall from running past your reach.

You can Redirect Flow on the waterfall to change where it’s going, but you can’t stop the flow. Likewise, you can’t create a current or flow in standing water (unless it’s deep enough that it naturally has them under the surface, but even then you could only redirect those).