Is this amulet of blinding fire balanced?

Question

I created the following item with a 5th level draconic (red) sorcerer in mind:

Blinding Fire Amulet

Wondrous item, rare (requires attunement by a spellcaster)

The amulet has a number of charges equal to the highest level of spell slot available to you. It gains all expended charges daily at dawn.

Whenever a spell you cast deals fire damage to a creature you can expend one charge to force the creature to make a constitution saving throw against your spell save DC, or be blinded for one minute. The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

I thought about the following modifications:

• Make it work on a spell rather than a single creature, e.g. all creatures damaged by a fireball. I am pretty certain, however, that I would need it to require multiple charges for this effect.
• Restrict the effect to spells of first level or higher. Not sure, if this is useful since there is already a limitation through the charges.
• Reduce the duration of the blindness to one turn, instead of (up to) one minute.

Question

Is this item abusable or is its description ambiguous? Is it wildly appropriate for the suggested level or rarity? Would one or more the of potential modifications indicated improve the item with respect to any of these points?

Answer 1

The item is somewhat overpowered, and can be balanced by reducing the effect or imposing a higher cost.

The item's description is mostly clear, although it has some ambiguities:

• In "the highest level of spell slot available to you", the "available to you" clause may have ambiguous interactions with items like a Ring of Spell Storing. It is also unclear whether "available" includes spell slots that have already been expended. A clearer phrase might be "the highest level of spell slot granted by your class features", or something similar.

• The term "your spell save DC" is ambiguous if the character has levels in multiple spellcasting classes that calculate spell save DC differently, such as wizard and cleric.

• As a small semantics nitpick, the item should regain charges, not gain charges.

Since the number of charges scales with the wearer's highest spell slot, the item would be powerful at any level of play.

Rarity is subjective, and has little impact on the item's mechanical usage in-game. "Rare" is fine.

Balance issues:

This item is equivalent to granting multiple free castings of a Blindness/Deafness spell. Thus the amulet effectively reproduces the spell effect, but without the action economy cost. The wearer can expend multiple charges to target multiple creatures, whereas Blindness/Deafness normally requires expenditure of higher level spell slots to do so.

Yet the amulet is even more efficient, since it can blind one creature per charge, whereas Blindness/Deafness can blind a number of creatures equal to the spell slot minus one. For example, a 5th level sorcerer could spend a 3rd level spell slot (and their Action) to blind 2 creatures with Blindness/Deafness. With your amulet, this sorcerer could instead spend that 3rd level spell slot to cast Fireball, and then blind 3 creatures who had taken fire damage. In theory, the amulet grants the benefit of a once-per-day Blindness/Deafness, cast at one level higher than the wearer's highest level spell slot, with the additional option of dividing it into lower level effects.

Also, unlike Blindness/Deafness, the amulet ignores limitations on range, line of sight, and line of effect. It could potentially blind targets who are unseen or have full cover, such as when Fireball damages a creature who is hidden behind a corner.

If the amulet applied to all targets of the spell, not just one creature, then its effect would be equivalent to higher level castings of Blindness/Deafness. For example, if the caster's Fireball inflicts damage on 8+ creatures, then expending one charge from the amulet would be akin to casting Blindness/Deafness with a 9th level spell slot. This modification would make the item significantly overpowered.

Another data point for comparison is the Gem of Brightness. While it can potentially blind multiple creatures, it does require an action to activate, it has a range limitation, and its charges are not renewable. Each activation is more powerful than one casting of Blindness/Deafness, even at higher level spell slots, but the overall item is balanced by its expensive activation cost.

Possible ways to balance this item:

• The effect should require "a creature you can see", not just "a creature". There should also be some range limitation, such as 30 or 60 feet, to make this item comparable to other spellcasting features and magic items.
• If activation had some action economy requirement, such as a bonus action or reaction, then you could balance the item via its opportunity cost. It's still better than casting Blindness/Deafness with the Quicken Spell metamagic, but at least this modification would force a tradeoff versus other options for the wearer's bonus action/reaction.
• If you reduce the duration to 1 round (i.e., until the end of the wearer's next turn), then the item's no-action cost could be justified, being almost comparable to a monk's Stunning Strike feature. Even one round of blindness can swing a combat encounter in the party's favor, especially if they're facing one or a small number of enemies.

Answer 2

It is different rarities at different caster levels

For the following analysis, I will address balance as if it gave you the ability to cast blindness/deafness x times per day, and then I will address action stacking and charge implications.

Comparing magic items that cast spells (or have spell-like effects) to instrument of the bards is helpful. When we do that, we see that at uncommon, (Fochlucan bandore), instrument of the bards has

• One 3rd level (fly)
• Two 2nd level (invisibility, levitate)
• Four 1st level (protection from evil and good, entangle, faerie fire, speak with animals)
• One Cantrip (shillelagh)

So from 1st to 6th level, blinding fire amulet gives less spell levels objectively. 7th+ the math changes, but it's probably relatively similar in power until 11ish.

Action Economy

The action economy is a significant thing to consider when designing effects of magic items. Consider that this item allows the attuned spellcaster an action surge. Even though they're just casting blindness/deafness, that's usually an action.

Magic item design pattern

The current design pattern of magic items is a certain amount of charges per dawn. This helps iron down what rarity an item should be, because magic item rarity is balanced around character levels.

Rarities I would assign based on the different charge amounts:

• 1st to 4th: Uncommon. It uses less spell levels than instrument of the bards (Fochlucan bandore), but allows blindness/deafness with no action.
• 5th to 6th: Rare. A significant bump in power here, not only with 3 uses per day, but with the option of fireball means that you can fireball a big group and blind 1-2 of them as well (because with the text of the magic item, you can use multiple blinds on one spell).
• 7th to ~14th?: Very Rare. Wall of fire gives the option of using this feature reactively instead of proactively, often more powerful, allowing you to only use the charges when you need to. Surround you and your party with a wall of fire and blind any who dare to walk through.
• 15th+: Very Rare - Legendary. I'm not sure where the cutoff should be here because there aren't any more spells that really change the way you'd use this magic item, but at some point being able to cast "mass blindness" with no action is very strong.

Suggestion

Giving this a constant charge amount would help its balancing. I would say 3 charges refresh 1d3 at dawn would put it at rare with the current effect based on my analysis above.

Answer 3

Thematically, it's a cool idea. Mechanically, it's... a bit strong.

Here are the issues I see with this.

• First, you are effectively granting a number of free castings of Blindness/Deafness (a level 2 spell) a number of times per day, except you can only chooses the blind option (which is by far the stronger option).
• The bearer gains a number of charges equal to their highest available spell level, so anywhere from 1 to 9, that recharge in full on a daily basis.
• They can reactivate the effect any time one of their fire spells inflict damage, including any spells that have a longer than instantaneous duration. Bonfire and Wall of Fire Immediately spring to mind as able to abuse this to force a target to make multiple saves against the effect.

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My recommendations:

• Cut it down to only 2-3 turns of blindness (only 1 turn is pretty bad IMO, especially depending on the initiative order), or have it at 1 minute with a new save at the end of each the creatures turns to end.
• Set the number of charges to a specific number, 3 is probably good in this case, as you're replicating a 2nd level spell that gets attached as a free rider to another spell. If the number of charges is that low, recharging to full every day is fine. If you set it higher, then go with something like 1d4+(max charges-4) recharged every day.
• Only allow it to be activated once per creature per spell, or if that ends up being to complicated, just once per spell, period.