I'd say no. The wording for the spell is horrible, but to target something you generally have to actually see it or know it's location somehow. (So maybe if it's behind a table but not in a room if you can't see it?) 

Otherwise you or enemies could dispel your buffs and spells from rooms away. You can't even see magic through walls with detect magic. Why would you be able to dispel through walls and barriers? You also can't counter spell without seeing the caster. Using those 2 spells as examples should set a good basis for this one. 

Otherwise... imagine scrying on the party, identifying their buff spells, then you dispel their spells from a hundred feet away through walls of stone. Or just saying oh yeah uh no that was dispelled, then having to explain that their magic was dispelled 7 rooms away by someone who knew they were in the vicinity. It wouldn't go over so well. If someone ran it like that fine, but expect the wizard to start spamming "antimagic nuke" in the radius if enemies were alert. Which is also, not a savory thought. 

So you're telling me that a puny level 5 wizard could go and dispel an ancient magical mountain that is been turned into a golem and has been roaming the lands for thousands of years???

Quote from Archangel_06 >>

So you're telling me that a puny level 5 wizard could go and dispel an ancient magical mountain that is been turned into a golem and has been roaming the lands for thousands of years???

Depends on if the transformation of the mountain into a golem is due to the effects of an ongoing spell.

For example (for argument's sake), if the mountain had somehow been targeted by the true polymorph spell and transformed with the object into creature effect into a golem, then yes, the golem only remains a golem due to the ongoing effects of the spell, that lasts until dispelled. In that case, targetting the golem with dispel magic cast at 9th-level, or succeeding on the DC 19 ability check, will cause the spell and transformation to end, and the golem would turn back into the mountain.

If however the mountain was animated as a golem through some sort of awakening like spell or effect, then the transformation is not the effect of an ongoing spell, since the spell's duration is instantaneous. Once awakened, the mountain has simply become the golem and the spell has ended as soon as it began, so there's nothing to be dispelled.

If the mountain is transformed through any other magical means that is not a spell, however spell-like or magical it is, it will not be affected by dispel magic, since RAW dispel magic only ends spells on the target. Entirely up to your own tables and DM discretion whether it can dispel anything else, like a mountain golem :D

So, Flesh to Stone, Ii would rule the effect was stopped thus preventing further progress of the spell from occurring. One would still need Greater Restoration to reverse/remove the effects of paralysis up that point.

I think its an aoe skill

So it would get rid of my fire / chill shield effect ? 

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.

 Incorrect. You are choosing to interpret that. It says you can target one creature, object or magical effect. If it mentions targeting one magical effect and you are reading this as it ends all spells, you are homebrewing. That is not what this says

things happened with this spell; my character drowned. 

Could you technically use it to disrupt or remove the ability of an arcane focus to channel magic?

Quote from BadhandsBob >>

Just curious, as a Sorc with twin spell meta magic, could I twin cast this and dispel magic on 2 target creatures? Dispel barkskin on a druid and haste on a fighter for example? Also I have a second question it says ANY spell of third level or lower on the target ends. Does this mean that all of them would? If a fighter had haste, barkskin and magic weapon cast on them by 3 different casters, would dispel magic remove all of them or one of them?

 Yes and Yes with the exception of magic weapon. If I remember correctly Magic Weapon is cast on the weapon not on the wielder and so Dispel Magic would have to be cast on the weapon.

You can target the creature ending all effects, negative and positive of 3rd level and lower. (Or higher if upcast.) That said, you can also elect to end one effect in specific if you instead choose to do so. 

The target of the spell is one creature, object, or magical effect, however "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" indicates that it is ALL spells on that target, so if your creature target has 2+ spells affecting it, then ALL will be attempted to be dispelled. ANY 3rd or lower spells are just gone, any 4th or higher the dispeller needs to make a DC 10+spell level check to remove.

That being said, the effects must be on the target itself so if the creature is standing in a fog cloud/darkness/illusion/other spell effect, that effect would not get dispelled since it exists independently of the creature, same as if they hold an object with light or another such spell, that objects magic would be unaffected.

is it possible to disable the magic properties of magic items with this?

Can you use dispel magic on a Construct?

Exactly. To counter any of these spells, you would need Counterspell.

Oof, using this on a Secret Chest would be horrible.

I just had a question regarding this spell. 

Can it be used to make a creature that was summoned with a spell disappear?

For example, by a celestial summoned by the spell "summon celestial"

And if so, do you have to target the one who summoned it or the creature or can it be both?

Quote from MisterG40 >>

I just had a question regarding this spell. 

Can it be used to make a creature that was summoned with a spell disappear?

For example, by a celestial summoned by the spell "summon celestial"

And if so, do you have to target the one who summoned it or the creature or can it be both?

This is clarified in the Sage Advice Compendium. Dispel Magic specifically ends spells, not the effects of spells. This means that the answer to your question depends on the duration of the spell used to create/summon the creature. If it's an instant spell like Animate Dead, then the spell is gone as soon as the thing is created, and there's nothing left to dispel. If the spell has a longer duration and the summoned creature only exists while the spell is active (like e.g. Summon Lesser Demons) then you can use Dispel Magic to end the spell early and thereby dismiss the summoned creature(s).

In your example, Summon Celestial is a spell that has a duration of 1 hour, and the summoned creature only remains while the spell is active. So, in this situation, yes, you can use Dispel Magic to end the spell early and eliminate the summoned celestial. (Though since it's a concentration spell, depending on the situation it may be more effective to force the caster to drop concentration by dropping a lot of damage on them.)

To answer your other question: with Dispel Magic you target the thing that's experiencing the effects of the spell, which in this situation is the summoned creature, not the caster that summoned it.

Rangers get no love. Unfortanate is what it is.

It's known how this affects spells. But what about magical effects that have a non-instantenous duration but are specifically not spells? Say, a druid is under the effect of wildshape or a twilight cleric is under the effect of steps of night. What if such effect is targeted?