How rare would you make this custom magic item?

[Spacehamster]

Endless vial of poison

Once per long rest you create 5 doses of a random poison(any from the phb rolled randomly).

The poison dissipates into mist after 24 hours or if outside 30ft of the vial for longer than 1 minute.
When you have used this power the vial refills at midnight.

Rare or very rare perhaps?

[Kadesh]

Rare, although with the proviso that no more than 5 doses of the poison can be in existence at once - creating more causes the first one of the 5 to be created to instantly disappear to prevent NI wealth shenanigans.

[Spacehamster]

Rare, although with the proviso that no more than 5 doses of the poison can be in existence at once - creating more causes the first one of the 5 to be created to instantly disappear to prevent NI wealth shenanigans.

Yeah that’s why I added that it disappears if outside 30ft from the magic item that created it for 1 minute, this let’s you use it on arrows since the arrow have time to reach the target before the poison disappears, and only one use per 24 hr.

[Ninja_Prawn]

random poison(any from the phb rolled randomly)

There's only one type of poison in the PHB, honey.

I'd be pretty leery about giving a random roll off the DMG list, too, since some of them are incredibly powerful and some of them are... not. Also some of them are gases, which might be hard to contain after you pour them out!

I'd make it a d6 list of poisons picked specific for the item. That way you can control the spread of their power levels, and make sure only liquids are on there. As for rarity, I'd maybe lean towards very rare depending on which poisons you put on the list, because this is a permanent item that will presumably not be using attunement... for some builds it'd be a really nice boon.

[Spacehamster]

There's only one type of poison in the PHB, honey.

I'd be pretty leery about giving a random roll off the DMG list, too, since some of them are incredibly powerful and some of them are... not. Also some of them are gases, which might be hard to contain after you pour them out!

I'd make it a d6 list of poisons picked specific for the item. That way you can control the spread of their power levels, and make sure only liquids are on there. As for rarity, I'd maybe lean towards very rare depending on which poisons you put on the list, because this is a permanent item that will presumably not be using attunement... for some builds it'd be a really nice boon.

Ah did not remember that all the poisons were in the DMG and not in the PHB. :)

[JackPhoenix]

There's only one type of poison in the PHB, honey.

Alcohol is also there. Ever heard the phrase "pick your poison"?

Also, Dagger of Venom is rare item, and gives you 2d10 + poisoned condition poison usable once per day.

[Lunali]

I'd make it a d6 list of poisons picked specific for the item. That way you can control the spread of their power levels, and make sure only liquids are on there. As for rarity, I'd maybe lean towards very rare depending on which poisons you put on the list, because this is a permanent item that will presumably not be using attunement... for some builds it'd be a really nice boon.

If you intend it to be used for weapons, there are only 4 weapon poisons in the list, given the wide disparity in power between them I'd just make the new magic item give a single type of poison and determine the rarity based on which poison it is, rare for drow or serpent, very rare for wyvern or purple worm.

If you intend it to be used in multiple ways, have it randomly determine from a few similarly powerful poisons of different types with rarity determined by how powerful the poison is.

[No brains]

Alcohol is also there. Ever heard the phrase "pick your poison"?

Also, Dagger of Venom is rare item, and gives you 2d10 + poisoned condition poison usable once per day.

Interesting to note, the Tankard of Sobriety on 139 of XGtE implies that alcohol isn't poison in this edition. It keeps a person from getting drunk, but it has no effect on poisons. This is interesting because a Dwarf's poison resistance doesn't actually keep them from getting drunk and it's possible to drink a poison-immune Yuan-Ti under the table.

What were we talking about? Yes, the Dagger of Venom is a good baseline. A more flexible poison pot that still takes an action to apply seems like it should be more rare, as DMG poisons can hit harder than just 2d10, even if they also need a Con save. Not to mention that taking an action to apply a poison allows it to be applied to other weapons than a dagger.

Does your custom magic item work with Fast Hands? Is applying the poison a 'use an item' action or is it 'using a magic item'? Deciding on this will influence if Rogues love, or just like this item.

[Sigreid]

Does the rarity matter? Seriously, if it's just an item for your table it only shows up when you want it to anyway.