What happens when you target a "magical effect" with Dispel Magic?

Question

In D&D 5e, the spell Dispel Magic says

Choose one creature, object, or magical effect within range.

The rest of the spell description explains that spells "on the target" of a level lower than that at which Dispel Magic was cast automatically end, and those of a higher level require a check.

This makes perfect sense when targeting creatures or objects which may have spells on them. But what does it mean to target a magical effect?

Does it mean that you can choose to target just one specific ongoing spell effect instead of stripping the whole shebang (clearing a negative spell from an ally with positive spells also in place, or a positive spell from an enemy who is under attack from a negative spell)?

Or, is this only for the special case of certain spells (like Imprisonment) which have effects which specifically mention being targeted by Dispel Magic, and since no effect is described otherwise? (This is a literal reading: a spell is a magical effect, but does not have spells on it, so the Dispel Magic effect has nothing to act on.)

Or — and I think this is a stretch — can magical effects which are not spells be dispelled by Dispel Magic? If so, what are the mechanics?

Answer 1

Dispel Magic Only Ends Spells

A magical effect that is not the result of an ongoing spell cannot be dispelled.

Jeremy Crawford has issued several Twitter rulings to this effect.

In this Tweet:

Q: Can dispel magic undo a druid's wild shape

A: Dispel magic ends spells. Wild Shape isn't a spell.

and this one:

Q: Does Dispel Magic auto work vs Channel Divinity powers? Ie.. Paladin's Vow of Enmity magic effect.

A: Dispel magic ends spells. A Channel Divinity option like the paladin's Sacred Weapon isn't a spell.

and this series of Tweets:

Q: Does dispel magic effect an arcane ward?

A: Dispel magic ends spells. Arcane Ward isn't a spell

Q: Does that mean magical items cant be dispelled either? We've assumed that they could be disabled temporarily with dispel.

A: Dispel magic can end spells that come from a magic item, but it has no effect on the item itself.

Also note that Dispel Magic can only end spells with an ongoing duration. It cannot remove the lingering effects of an instantaneous spell. PHB P. 203:

Many spells are instantaneous. The spell harms, heals, creates, or alters a creature or an object in a way that can't be dispelled, because its magic exists only for an instant.

The March 2016 Sage Advice Column covers Dispel Magic as well. It reiterates that Dispel magic cannot end magical effects that are not the result of a spell, such as a vampire's Charm effect. It also reiterates the rule about Dispel Magic not working on the results of a spell with an instantaneous effect. It adds that a readied Dispel Magic cannot be used in place of a Counterspell, though in some limited circumstances, it may be almost as good.

To answer your actual question, in this context, targeting a magical effect clearly means you can target just one specific ongoing spell effect instead of stripping everything on a particular creature.

Answer 2

Most Magical effects require spells to create them in the first place.

If it is unclear which spell and what level created a specific magical effect, it would then be completely within the purview of the DM to determine what the effective spell level of the effect is and how high of a slot of Dispel magic is needed (or the DC in the case that an insufficiently high slot is used).

If it's not clear that a spell created the effect (such as being from a CD effect or a class feature not directly tied to a spell), it's effectively left to the DM to determine A. if it is a magical effect and B. what the effective spell level of said effect is. I think there are strong arguments that both Wild Shape and Channel Divinity are L1 spells, but that's a discussion I would be very willing to bend on if a compelling argument is made.

This slot is not known by default but I would definitely allow it to be discovered by one or several Intelligence(Arcana) checks.