Do you need to take the Hide action when you are Invisible, make no noise and leave no traces?

Question

The Situation:

Lets say you are under the effect of Invisibility.

An invisible creature is impossible to see without the aid of magic or a special sense. For the purpose of hiding, the creature is heavily obscured. The creature's location can be detected by any noise it makes or any tracks it leaves.

And you are wearing the Boots of Elvenkind

While you wear these boots, your steps make no sound, regardless of the surface you are moving across. You also have advantage on Dexterity (Stealth) checks that rely on moving silently.

Now your groups ranger or druid casts Pass Without Trace on you.

[...] can’t be tracked except by magical means. A creature that receives this bonus leaves behind no tracks or other traces of its passage.

My Question(s):

I know that when you are Invisible and you did not hide, you are still detectable because of the noise and the track you leave behind. But the Boots of Elvenkind and Pass Without Trace take care of that. So:

1. Are you still required to take the hide action in this situation if you don't want enemies to know your location/presence?
2. If so, why? What gives away your location?
3. If not and you are under the effect of greater Invisibility do you get the benefits of "Unseen Attackers and Targets" for every attack you make when you move between attacks? (You would give away your location, but are not detectable, so completely hidden again when you move)

Answer 1

1. Yes, you would still take the Hide Action, as written. Even though your footsteps are silent, you would still make some other noise, such as your clothes rustling or the sound of your sword swinging. This would count as "any sound" by which to be tracked. (I wouldn't run it that way, but as written, I think that counts) I believe that the Hide Action would involve your character moving to some degree, and so should get advantage from the Boots of Elvenkind.

2. Part of 1

3. Even if they know your exact location, you are invisible. This means you're unseen, so you get the benefits of Unseen Attacker.

Answer 2

Yes, you need to hide.

Others have mentioned sounds that are not from your footsteps, but from other sources like breathing, clothes friction, scabbard banging against your armor and so on.

I intend to include pass without trace in this answer. This spell hides your tracks after you have moved on, not while you are present.

A few examples:

1. Standing on a soft carpet will make imprints in the carpet, but as soon as you move on the imprints will vanish. Hiding in this case is knowing not to stand on the carpet.
2. (Accidentally)Stepping on a sleeping goblins face will hurt him. When checking the mirror he will not find any boot imprints on his face, but the damage doesn't heal and he knows something was there. Hiding in this case is being extra careful when positioning yourself between the sleeping goblins.
3. Bad smell. If you(the observer, not hid-ee) arrive home to your house and something smells really bad in your living room you may want to investigate. This doesn't mean you are aware that there is a hidden creature there, but you know something is in the room. If the creature leaves the room then the bad smell will vanish suddenly as pass without trace does its magic. Hiding in this case could include cleaning your boots after wading through the sewers and before entering someones house. Or if the room is large enough then the observer may not get close enough to the hid-ee to smell him.
4. Getting out of the way. Invisibility, boots and pass without trace won't help if someone opens the door and smash it right into your face. Or maybe someone suddenly decides to open the window and the hid-ee has to scramble to get out of the way and knocks something over. Hiding in this case is to position yourself to lessen the chance of someone accidentally impacting your location.

Pass without trace also gives a +10 to your stealth checks in addition to the advantage from the boots so all in all it will be hard to find a character that has done the hide action, but it is possible.

If you are invisible then you are also unseen.

Note that there can be different outcomes of stealth checks depending on your GM and the play style. The observer may know something is in the room, he may know where something is, but not what it is. He may know there is an invisible humanoid somewhere in the room or he may know both what it is and where it is.

Answer 3

1&2) The sidebar HIDING on PHB p. 177 says specifically:

An invisible creature can always try to hide. Signs of its passage might still be noticed, and it does have to stay quiet.

Boots of Elvenkind have the effect you described in your question:

While you wear these boots, your steps make no sound, regardless of the surface you are moving across. You also have advantage on Dexterity (Stealth) checks that rely on moving silently.

Dexterity (Stealth) checks are described as follows:

Make a Dexterity (Stealth) check when you attempt to conceal yourself from enemies, slink past guards, slip away without being noticed, or sneak up on someone without being seen or heard.

Neither Invisibility nor Boots of Elvenkind state that you are actually hidden without taking the Hide action. This makes sense because (as the other answers have pointed out) your footfalls being difficult to detect does not mean that the rest of your movements are noiseless and that you are scentless. The benefit of your Boots is reflected by gaining advantage on rolls, and Invisibility gives attackers that rely on sight disadvantage when attacking you.

3) Unseen Attackers and Targets on PHB p. 194 says:

When you attack a target that you can't see, you have disadvantage on the attack roll. This is true whether you're guessing the target's location or you're targeting a creature you can hear but not see... when you make an attack, you give away your location

So if a creature effected by Greater Invisibility were hidden ("both unseen and unheard") and hadn't attacked, you would have to guess the target's location and then attack with disadvantage. Once the creature attacks, you know its location, but you still attack with disadvantage. The attacker would then need to take the Hide action again to become "both unseen and unheard." They would have advantage on the roll and could do it anywhere because of the effects of Invisibility and Boots of Elvenkind.

Answer 4

No

There are circumstances that do break down the RAW. E.g. a flying, invisible character in the area effect of a silence spell - He cannot be perceived by normal sight, doesn't leave any tracks because of fly and doesn't make any sound because of the silence spell. Having that character take a Hide action and roll for stealth just makes no sense. He is effectively "auto-hidden".

Here is an example that I had from Princes of the Apocalypse adventure (small spoiler alert!)

We fought the air prince in a final epic battle who had managed to deafen us for 1 minute, had flight and positioned himself in a fog created by his cloudkill spell. No invisibility was cast yet he was heavily obscured (invisible), left no tracks (fly) and we could not hear him make noise (deafened condition). There was no way for us pinpoint his location for about 7-8 rounds.

Answer 5

No

Nothing in the rules says that a creature can hear/smell well enough to automatically track a moving invisible creature. Doing so would be close to giving them blindsight.

It's reasonable for a DM to assume that a non-deafened creature in a non-silenced area can do so against something not moving particularly stealthy with their passive perception.

Tracking a creature in the heat of battle by other incidental noises other than footsteps is not so easy. At DM could justifiable call for a Perception check and set the DC as they see fit. I wouldn't call for a stealth check, because your not taking the time to be stealthy. You're just running and hoping.

The rules support this in the section under Unseen Attackers and Targets

Combatants often try to escape their foes' notice by hiding, casting the invisibility spell, or lurking in darkness.

This implies that in some circumstances being invisible is equivalent to being hidden.