Is this homebrew "Faerie Fire Grenade" unbalanced?

Question

I am playing a druid in my friend's Waterdeep: Dragon Heist campaign. He is allowing me to do some things with exotic plants that I found in the wilds. One of those plants was one that shed a yellow dim-light, which was found beneath the sea.

So, I asked him if it was possible to make some sort of grenade that exploded using some sort of glue along with the powder of this plant, simulating an effect of the spell "Faerie Fire".

At first we both found it interesting and he allowed me go ahead and make it. The mechanics of the Grenade is as follows:

• The Grenade can be thrown up to 30 feet away;
• When it explodes, the grenade releases a sticky powder in a 20-foot cube;
• Any creature in the area that fails the Dex saving throw is outlined with yellow light, and is subjected to the same effects imposed by the "Faerie Fire" spell.

The DC of the grenade depends on how well I roll in the tool check to craft it, but it's up to 15, with the ones I crafted having 12 and 13.

But after a while I pondered about the pros and cons of that grenade in comparison to the spell, which sums up as follows:

Cons

• The grenade has a lower DC than if I cast the spell (my spell save DC is 14)

Pros

• A non caster can use the grenade and get the same effect
• The party doesn't spend a spell slot
• It doesn't require concentration

Now, regarding the fact that we save a spell slot and it doesn't require concentration on it, I start to think that the grenade, besides having a lower DC, is strong. I wouldn't say it's game breaking, since I'm not mass producing it (I don't have interest in doing that and the DM won't allow it), but is still strong.

But there are others similar consumable items that also simulate the effects of spells without spending spell slots or requiring concentration.

Is this item really unbalanced in comparison with other similar consumable items? If it is unbalanced, how can I balance it? Are there any effects (positive or negative) of this item that I'm not taking into account?

The Grenade doesn't have a gold cost to craft, since I'm allowed to make it by harvesting the plant, which I grew with Druidcraft, and, for now, the cost of the component for the explosive and glue have been ignored. The only limitation that is applied is time, since I have to growth the plants.

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For reference, I took a look at the Dust of Disappearance, which is an uncommon magic item, that, at some extent, simulates the Invisibility spell, and took the following notes about dust of disappearance:

Cons

• While the spell have a duration of 1 hour, the dust duration is up to 2d4 minutes.

Pros

• It turn all creatures within 10 feet of you invisible (up to 13 creatures), while the spell turn only one.

The pros of our grenade also applies to this item as well.

Answer 1

It's slightly overpowered

I think you're completely right in how well it's balanced against other magic items, such as Dust of Disappearance, however due to its relative ease of production, it'd be more appropriate to compare it to common items, such as Alchemist's Fire. When comparing Alchemist's Fire to 1st level spells, Witch's Bolt stands out as an apt comparison, doing a similar damage-over-time-unless-mitigated effect. Alchemist's Fire, however, does significantly less damage, at the tradeoff of being more troublesome to remove. This item is instead a stronger version of Faerie Fire, without any immediate drawbacks. It needs some drawback to be more balanced, perhaps the ability to wipe it off (like Alchemist's Fire), to only last 1d4 rounds, or to lose the effect once the target moves 30 ft.

Furthermore, at a price of 50 gold per vial, if comparing it to Alchemist's Fire, it should take 40 hours of work to produce one vial, according to the downtime activity rules on page 128 of Xanathar's Guide to Everything.

Answer 2

It’s better than a scroll of Faerie Fire

1. It can be used by anybody, not just bards, druids, artificers, light domain clerics and archfey warlocks
2. It doesn’t require concentration

These are both powerful advantages but it’s a single use item that turns a few misses into hits and affects 1 combat.

If you could only produce these in limited numbers this would be fine. However, if you can give each party member 2 or 3 it’s way too powerful. Alternatively, if the effect could be ended by using an action to wipe the stuff off, that would probably by ok too.