It specifically says choose one effect in the intro sentence. I would most likely rule it as 1:1 ratio per casting.

Easy, you can form a mental image of where the effect is. However you first have to be aware of the effect. You can't just walk into a room and try to dispel invisibility. 

Quote from HimoMistwind >>

It specifically says choose one effect in the intro sentence. I would most likely rule it as 1:1 ratio per casting.

 Sorry but that's not entirely true, the wording has a few key elements against that: Choose one creature, object, or magical effect within range. Any spell of 3rd level or lower on the target ends. For each spell of 4th level or higher on the target, make an ability check using your spellcasting ability.

Those words imply to me unless you are specifically targeting one magical effect you attempt to remove any and all spells affecting that target, buff, debuff or otherwise.

But yeah honestly still weirded out by dispelling Darkness, especially if you are inside said Darkness at least, cause you wouldn't know if the Darkness is underneath you, beside you, above you... no direction at all, but you can just target the magical effect? That said the same is also true of casting it on an object near someone... especially if the caster moves the object.

How would Dispel Magic work in these circumstances?
A. A cleric is concentrating on a Bless spell which is active on three targeted allies. Would the Bless effect end for all targets?
B. A wizard enchanted three objects with one spell. Would one object or all three lose the magical effect?
As a DM, I decided that Dispel Magic acts on a spell, not simply a single effect. Counterspell is much clearer in its language in this regard.

Quote from Merikariu >>

How would Dispel Magic work in these circumstances?
A. A cleric is concentrating on a Bless spell which is active on three targeted allies. Would the Bless effect end for all targets?
B. A wizard enchanted three objects with one spell. Would one object or all three lose the magical effect?
As a DM, I decided that Dispel Magic acts on a spell, not simply a single effect. Counterspell is much clearer in its language in this regard.

 

 

Beyond 20

 

 

 

 

 

 A) Dispel magic states "the spell ends", so the bless spell would simply end on all targets, not just the one you targeted. 

B) If it was an ongoing spell then again, casting dispel magic would end the spell and thus disenchant all items. But this does depend what you mean by "enchant". For example if they were made living via animate objects, the spell would end and all 3 would become mundane items again. If by enchant you mean something like crafting a magic item with a ritual, this spell would have no effect because there are no "spells" currently affecting those items. They just happen to be magical now. 

Ofcourse your DM has final ruling on this and dispel magic is totally something I can envisage creative non-standard uses for. 

It depends on if the Flesh to Stone spell was concentrated for the full amount of time necessary to make them petrified after concentration drops. Once the effect is stuck, dispel magic wouldn't work on it, as it requires a spell or effect that can remove the petrified condition.

Think of it this way, as the spell is concentrated on, there is an active magical effect that can be interrupted by dispelling it. But if the effect ends after taking effect, there is no active magic to dispel. The target simply has had their body altered. It's weird to think about but that's the best way to explain it that I know of.

If a vampire charms a target using its ability, can it be dispelled? Is it technically a magic effect?

Can an effect or an object creating a pocket dimension (as a bag of holding) be dispelled from inside said dimension ?
Ex : A wizard trapped inside a bag of holding trying to dispel the bag to get out.

I

Syntax and word-nerding

I should not be doing this, I have a session to prep for as I am the DM.
However...: This has got to be one of the worst grammatically written spell description in the book (inside which, there are numerous bad examples). The 'AHL:' section makes it even worse. 

Taken individually, the sentence starting with 'Any' should suggest a single target of magical property, ie - magical effect, object, creature. However, the next sentence makes that uncertain with the usage of 'For each... on the target'. These two sentences alone can suggest that when casting this spell, the target, if it were, say, a lich, could lose all magical effects on it, whether there is 1 or 500. This would mean many many rolls. The reasoning is that the use of "any" instead of another determiner or signifier can be ambiguous. Generally the context should explain. The additional question is, does the use of the word "any" mean that it can never remove ALL the effects? Any should never be used to refer to all of a number of things. (Def below)

Any - "used to refer to one or some of a thing or number of things, no matter how much or how many."

The big issue is not the use of 'Any' but the choice to not use 'Every'. If it read: ''Every...", "For each...", "At Higher Levels. ... of a spell on a target..." then there would be almost no question as to what it means. Even better would have been "One or more..." if that was the intent. 

However, if the intention is that you can use this spell to target one or more effects on a target, as in removing 'Slow', but leaving 'Darkvision', then this usage once again makes sense, but should have included more definition for clarification. 

As to the AHL at the end, if this is to help clarify the meaning and usage as a whole, then it seems to conflict with "For each...", if however the intention is to add a new functionality to the spell when using it at higher levels, then it stands alone and does not help with the clarification of the main body of text.

.....

as a DM, I would seriously consider limiting the ending of effects to a number per turn, simply for the nature of the IRL rolling problem. like a maximum of 20 or something just to save time. 

That being said, the Rule of Fun should always be used at every table. 

What happens when you cast this on a potion? Does it permanently remove the effects or just subdue the effects?

No, a potion is a permanent magic item, it's not an ongoing spell

It used to be that Dispel Magic suppressed the powers of permanent items for a certain amount of time, but not in this edition.

Fun fact - A CHA-based caster under the influence of Glibness can choose to Take 15 on their Dispel Check. With a maxed-out primary stat, that's enough to guarantee to dispel anything, even before you factor in Guidance/Jack of All Trades/etc

Quote from BrisingerDramr >>

What level can a sorcerer learn this spell?

(Not lvl 1)

 Sorcerers get 3rd level spells at 5th level.

Quote from theOnlyBarber >>

Can an effect or an object creating a pocket dimension (as a bag of holding) be dispelled from inside said dimension ?
Ex : A wizard trapped inside a bag of holding trying to dispel the bag to get out.

 No, but they might be able to use Anti-Magic Field, which depending on your DM, would either make all the items pop out, or close the exit. If the bag is open, Misty Step would be cheaper and more reliable, otherwise you would need to use Gate or Plane Shift to get out, so hope your wizard has a tuning fork or 9th level spells!

It says make an ability check using your spellcasting ability.

So not proficiency but intelligence modifier if you are a wizard for exemple.

Up to the DM, but generally I would say no.

Quote from Dragonfiremalus >>

Yes, as written it's all spells on the target, making Dispel Magic perhaps the most underappreciated incredibly powerful spell in the game.

 And it's bit of use for war magic wizards

Quote from Damonies >>

Tried to use this to destroy a construct. Did not go well. 

 good idea

As far as I am concerned, you do not have to see the target. So my question is, if the target is inside a room or have any type of coverage, within range, I would be able to disple the target's magical effects?

Like counterspell, if you cast it at or above the level of the effect on the target, it is automatically dispelled. But if you cast it at 5th level, and the effect is from a 7th level source, the check would still be DC 17.