Does an Echo Knight fighter's echo provoke an opportunity attack when it moves?

Question

Does an Echo Knight fighter's echo provoke an opportunity attack when it moves?

The Echo Knight fighter's Manifest Echo feature says, in part (EGtW, p. 183; emphasis mine):

At 3rd level, you can use a bonus action to magically manifest an echo of yourself in an unoccupied space you can see within 15 feet of you. This echo is a magical, translucent, gray image of you that lasts until it is destroyed, until you dismiss it as a bonus action, until you manifest another echo, or until you're incapacitated.

Your echo has AC 14 + your proficiency bonus, 1 hit point, and immunity to all conditions. If it has to make a saving throw, it uses your saving throw bonus for the roll. It is the same size as you, and it occupies its space. On your turn, you can mentally command the echo to move up to 30 feet in any direction (no action required). If your echo is ever more than 30 feet from you at the end of your turn, it is destroyed.

The rules on opportunity attacks state (emphasis mine):

You can make an opportunity attack when a hostile creature that you can see moves out of your reach. To make the opportunity attack, you use your reaction to make one melee attack against the provoking creature. The attack occurs right before the creature leaves your reach.

The description of the Manifest Echo feature does not state that the echo is a creature, so am I correct to conclude that the echo wouldn't trigger an opportunity attack?

Answer 1

The Echo does not provoke opportunity attacks.

You pretty much highlighted all the relevant text:

This echo is a magical, translucent, gray image of you

And

You can make an opportunity attack when a hostile creature that you can see moves out of your reach

The echo is an image and not a creature, hence it does not provoke opportunity attacks.

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By contrast, the spell simulacrum creates an illusory duplicate that is partially real, but in this instance the spell defines that image as a creature. The echo knight's Manifest Echo does not define it as a creature.

Answer 2

The Echo does provoke opportunity attacks

To start with, creature is not a strictly defined term in the game. Since D&D 5e uses natural language as opposed to strictly defined language, we need to figure out whether or not it "walks like a duck" so to speak.

But we have some clues it should be counted as a creature:

1. It has an AC and Hit Point(s), so it can be hit and interacted with
2. It has explicit immunity to all conditions

The second point is important, as conditions are described as (emphasis mine):

Conditions alter a creature's capabilities in a variety of ways [...].

If it's not counted as a creature, then it doesn't need to have the immunity specified, but it does, so it must be capable of being targeted by conditions. Ergo it is a creature, and is affected by all things that creatures are.

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Even ignoring the fact it counts as a creature, you are missing a paragraph from the opportunity attack description that is relevant to the Echo Knight Echo:

In a fight, everyone is constantly watching for a chance to strike an enemy who is fleeing or passing by. Such a strike is called an opportunity attack.

It definitely counts as an enemy, and it can definitely move out of your reach. An opportunity attack is fundamentally a strike at a thing your character considers to be an enemy that is moving out of their reach. By saying that the Echo doesn't trigger opportunity attacks you are either saying:

1. It cannot be damaged because it's an image, not a creature, which is absurd given that it has Hit Points and an Armor Class, and therefore can clearly be damaged.
2. It is somehow invisible, or undetectable to creatures whose space it is in, which is also absurd, since it is described as:

This echo is a magical, translucent, gray image of you

The remainder of the opportunity attack rules are describing how you mechanically effect the opportunity attack. These mechanical effect rules were written before the Echo Knight was, and didn't envisage something threatening, that can move out of your attack radius, with an armor class and hitpoints, not being a creature.

Answer 3

The language is unclear

The language around the Echo Knight does not give us a clear answer here. Usually, creatures are called creatures and other mechanics are called out for what they are as well.

A good case is Bigby's Hand, which states that the Hand itself is an object. Yet the object does have HP, AC, and can be moved. However, because it is an object there is no opportunity attack as that requires a creature.

However, the stat block for the Echo doesn't actually say what it is. It doesn't call it creature. It doesn't call it an object. It just calls it

...a magical, translucent, gray image of you

This is pretty unclear. It does have HP, AC, and can move, which seems creature like. But the example above of Bigby's Hand shows that you can have those thing and be an object, which results in not being able to automatically assign things that have those attributes to be creatures. They could just as easily be objects.

So what do we do?

Well, calling it a creature by lack of information doesn't really make sense for me. Calling it an object (or something else) equally doesn't make sense.

What we generally need to do is look at similar mechanics, such as Bigby's Hand and spiritual weapon. Those two spells create similar effects and neither produce a creature, therefore neither of those mechanics generate Opportunity Attacks.

We can also look at animate objects, which specifically creates a creature. Without that specific statement of "this creature", I don't think it's unreasonable to assume that it is.

But with the lack of clarity, if it works for a table to have it do so, then it works. Just to be aware, this decision does add a limitation to the mechanic. With only 1 HP and an AC of 14, the echo won't last long if it draws more attacks simply by moving.