How does the Gloom Stalker ranger's Umbral Sight feature interact with this silent magic dagger?

Question

I'm currently playing a ranger in a 5e module, and have gained a magic dagger that

doesn’t make noise when it hits or cuts something.

The dagger is

Reszur from Princes of the Apocalypse (p. 157). It is found by the dwarf statue (area T7) in the Tomb of Moving Stones.

The Gloom Stalker ranger's Umbral Sight feature (XGtE, p. 42) says:

You are also adept at evading creatures that rely on darkvision. While in darkness, you are invisible to any creature that relies on darkvision to see you in that darkness.

I'll be getting Umbral Sight next level, so I want to know how they will both work together.

The Unseen Attackers and Targets rule says (emphasis mine):

When a creature can't see you, you have advantage on attack rolls against it. If you are hidden–both unseen and unheard–when you make an attack, you give away your location when the attack hits or misses.

With this dagger, is it possible to not give away your location when you miss? If so, does it still work if you hit? Or is this really a DM-to-DM thing?

Answer 1

You remain invisible - but not because of the dagger

Let's look at the situation you are describing. We'll assume you are in an environment that qualifies as non-magical darkness and are fighting a creature with darkvision.

In this scenario, umbral sight is what matters.

You are also adept at evading creatures that rely on darkvision. While in darkness, you are invisible to any creature that relies on darkvision to see you in that darkness.

It does not state that you lose the invisibility after the attack. This is an always-on ability that happens in this type of environment.

Whether or not you hit, miss, or do anything else doesn't matter. You will always be invisible and unseen in this environment (unless something changes.)

In other environments, it may matter

The text of the dagger dictates that it only makes no sound when you hit or cut. If you miss, the dagger 'sounds' normal. How this plays out will likely be up to a DM.

Interaction with being Hidden

Since you quoted the rules around being hidden, let's address that case.

Your ranger is in darkness and has taken the action to Hide. Your roll is sufficiently high to beat the passive perception of your enemy. You are now Hidden and invisible. Very cool!

Now, you take out your dagger and attack (with advantage)!

You roll and miss - hidden has ended

As the dagger makes a normal noise, you lose your hidden status but remain invisible. As you've quoted, the dagger's special soundless property doesn't engage when you miss, only if you hit or cut.

At this point, the enemy knows your location and can attack it with disadvantage because you are no longer hidden (but still invisible.)

You roll and hit - up to a DM

Here is what it gets a bit trickier. The rules talk about being hidden as unseen and unheard. However, they also follow up with:

...you give away your location when the attack hits or misses

Normally, you'd give yourself away at this point and lose your hidden status (but still remain invisible.) What's tricky is you are still invisible (unseen) and because you hit, the weapon didn't make a sound.

I hate to say it, but in this case it's going to be a up to a DM as to whether you lose your hidden status. A DM can rule that while the blade makes no noise, you do (because you can still make noise even if the blade doesn't.)

That ruling does seem to take away from the weapon's properties though. A DM could instead rule that because the weapon is soundless and you are invisible, the attack doesn't give away your location and you remain hidden.

Because you are still hidden, the creature has to guess your location and still make an attack at disadvantage. If you've moved away (with no Opportunity Attack because you aren't seen), then they are very likely to not hit you unless they luckily guess your location.

Answer 2

The rules don’t say that you give away your position “because of the sight and sound” of the attack, the just that you give away your position. So eliminating the sight and sound of the attack doesn’t do anything, under the rules.

Could a DM rule that someone completely unable to perceive the attack in any way cannot glean your position from a missed attack? Certainly. They might even allow it if the attack hits for a ranged attack. But that’s purely up to the DM; the rules don’t suggest it.

Answer 3

It is not possible.

As you note, the rules for attacking while hidden state that "If you are hidden when you make an attack, you give away your location when the attack hits or misses." This is fairly conclusive, but maybe you have found an exception;

Using Umbral Sight has the following effect: "While in darkness, you are invisible to any creature that relies on darkvision to see you in that darkness." However, an invisible creature's location is still known via non-sight senses, so no luck here.

The magic dagger says "doesn’t make noise when it hits or cuts something", but it does not prevent you from making noise or being detected by other senses--your clothing and footsteps as you attack, the target can smell you, they can feel the air move as you swing, they feel the force of the attack. Unfortunately this doesn't override the rules either.

As always, you may be able to convince your DM to overrule the rules, but don't count on it.

However, maybe that doesn't matter

It's not clear to me what you are trying to accomplish. Whether you are hidden or using Umbral Sight, at the end of the attack you remain unseen. This means you can freely move away from the target since you can't take an Opportunity Attack against a target you can't see.

If you just want to end your turn in an unknown location, then if you are hidden you just need to save 5ft of movement, then you can take a step in any direction (other than onto the enemy's location) and they will be left guessing.