What the hell is the metronome?

[Blaaticus]

I understand that it gives you a random item for one room, but a good amount of the items have a tendancy to be permanent.

[Dad Poets Society]

The item has gone away upon entering a new room anytime I've used it.

[Blaaticus]

Originally posted by Dad By Daylight:

The item has gone away upon entering a new room anytime I've used it.

Whenever i used it, most went away. However, Tech baby, Dr. Fetus, Epic Dr. Fetus, and a few other familiars stayed with me the entire run.

[Arghaab]

According to the wiki, the item is bugged at the moment.

When used, it grants the benefit of a random item for the duration of the current room.

However, if the random item is directly modifying your Tear Delay stat, your Tear Delay will remain changed untill you pick up another item modifying your Tear Delay.
If the item also modified your other stats, those will be back to normal after the current room.
If the item also had some kind of special properties (like Dr. Fetus, wich change your tears into bombs), those will remain even after you pick up another item modifying your Tear Delay.

For example, the item Polyphemus changes your Tear Delay, your Damage, and gives you the property of Piercing Tears if your tear kills an enemy.
If Metronome gives you Polyphemus :
- Your Damage will be boosted for the current room
- Your Tear Delay will be slowed untill you find an item that modify your Tear Delay again. At that point your Tear Delay won't take into account the Polyphemus modifier anymore.
- You get the Piercing Tears effect untill the end of the run.

[Daemonologist]

Originally posted by Arghaab:

According to the wiki, the item is bugged at the moment.

When used, it grants the benefit of a random item for the duration of the current room.

However, if the random item is directly modifying your Tear Delay stat, your Tear Delay will remain changed untill you pick up another item modifying your Tear Delay.
If the item also modified your other stats, those will be back to normal after the current room.
If the item also had some kind of special properties (like Dr. Fetus, wich change your tears into bombs), those will remain even after you pick up another item modifying your Tear Delay.

For example, the item Polyphemus changes your Tear Delay, your Damage, and gives you the property of Piercing Tears if your tear kills an enemy.
If Metronome gives you Polyphemus :
- Your Damage will be boosted for the current room
- Your Tear Delay will be slowed untill you find an item that modify your Tear Delay again. At that point your Tear Delay won't take into account the Polyphemus modifier anymore.
- You get the Piercing Tears effect untill the end of the run.

Assuming that's accurate basically there's 2 issues with the item:

1) The tear delay cache isn't updated when you leave the room, ending the effect, this is the same issue that affected many other items in the past for various stats and is a simple enough fix for the devs. If you have the cancer trinket you could just drop it and pick it back up to refresh the cache, otherwise you'd be stuck waiting for another tear delay (not tears up/down - they're separate despite both affecting fire rate) item.

2) Tear modifiers aren't removed at all - as some tear modifiers override others and some can be obtained from multiple different sources this might actually be intended or a temporary solution to avoid potentially having it remove modifiers you should actually still have after the room ends due to other items. On the upside, most of these are positive in almost any situation.