Magic item crafting: costing spell permanence and charges

[Zhorn]

So the discussion of making custom magic items came up in my game last week and I've told my players I'd look into setting up some versatile rulings for making items not listed in a sourcebook. The mindset I'm going with is if there is a spell which can produce a similar effect, then making a magic item do it should be a possibility.

Already fiddling about with cost formulas for scrolls (a mix between the AL spec services formula and a variation on xanathar's scroll crafting rules, there'll be a post in homebrew at a later date when i'm happy with it), figured I can use that to work out a base enchanting cost for custom magic items.
Charges, recharging and spell permanency has me a little stumped.

For the sake of a consistent benchmark, to make a single cast scroll that doesn't require material components I have:



Spell Level
Crafting Cost
Equivalent Rarity


Cantrip
25 gp
Common


1st
50 gp
Common


2nd
100 gp
Uncommon


3rd
250 gp
Uncommon


4th
500 gp
Rare


5th
1,000 gp
Rare


6th
2,500 gp
Very Rare


7th
5,000 gp
Very Rare


8th
10,000 gp
Very Rare


9th
25,000 gp
Legendary



And magic item crafting cost is somewhere between the DMG (p129) and XGtE (p129). The final numbers can be tweaked to a different price point, this is just to gauge a relative price model.

So using this as the starting point, what scaling factors should I look at for spells that can be cast multiple times via charges and recharging, or unlimited use items that activate for a duration, or always active?

Just thinking out loud here:

Magic Weapon (2nd level spell) for a +1 bonus (scroll cost 100 gp)
+1 weapon in the DMG: Uncommon, so valued ~200 to 500 gp
cost multiplier of ~2-5, call it x3.5 to make that +1 bonus always on, seems to line up nicely.

BUT

Flame Blade (2nd level spell) does 3d6 fire damage on hit (scroll cost 100 gp)
Flame Tongue in the DMG is a close equivelent with 2d6 fire damage on hit: rare, looking at a value of ~2000 to 5000 gp.
Using that x3.5 from the previous example is way to low compared to the existing in game equivalent.

Ideas? Any understanding of the system used to value the existing magic items in the DMG, or how to reverse engineer them into a formula?

[Unoriginal]

Personaly, I much prefer the act of spellcasting and the act of magic item crafting to be more separate than that. As per the Xanathar's rules, you can craft a wand of Sleep without even being able to cast a cantrip. Not to mention plenty interesting magic items do not duplicate the effects of spells, or only in some parts (ex: Winged Boots aren't the same as a Flight spell).

That being said, my advice is to take items that do allow you to cast a spell (ex: Necklace of Fireball) and give the same magic item rarity to all spells of the same level. It's not perfect nor very flavorful, but it's simple to do and use.

[Haydensan]

I would be careful about allowing crafting of 6th level spells and higher. They are very strong and there's reason you only have 1 slot of each for most of your career when you eventually get to the capability of casting them.

[Zhorn]

Personaly, I much prefer the act of spellcasting and the act of magic item crafting to be more separate than that. As per the Xanathar's rules, you can craft a wand of Sleep without even being able to cast a cantrip. Not to mention plenty interesting magic items do not duplicate the effects of spells, or only in some parts (ex: Winged Boots aren't the same as a Flight spell).

to clarify, I'm not saying they need to be able cast the spell themselves, it's just a guide line of "this type of spell exists, so a similar effect should be able to be produced by a crafted magic item".
Also, this isn't a thing I'm making to hand over to the players and just say "Have at it". It's intended as a tool behind the DM screen to set a reliable standard on what prices/values I set on the projects players want to undertake.
It's all a work in progress thing, and there's going to be a lot of small things to address at different points before I use it.

But for now, I'm just looking at getting a good scale for converting a single spell cast into either charges/recharges, or permanence/unlimited uses.


That being said, my advice is to take items that do allow you to cast a spell (ex: Necklace of Fireball) and give the same magic item rarity to all spells of the same level. It's not perfect nor very flavorful, but it's simple to do and use.
A simple option, yes. But it doesn't really help with my underlying goal of have a value for going from a single use into multiple uses. It might not every come up in my current campaign, but I still want to have it ready.
It's more satisfying at my end to answer my players inquiries about wanting to do something with a 'yes and' or 'you can try' rather than 'I don't have a rule set for that, so no'


I would be careful about allowing crafting of 6th level spells and higher. They are very strong and there's reason you only have 1 slot of each for most of your career when you eventually get to the capability of casting them.

All going to plan, I'm aiming to have a system where the high level spells should be costly enough that if they were to make an item using any, it would be just one for the entire group for the whole adventure, but still possible.
And if it blows up the campaign, lesson learned. I'll just give the players a deck of many things, throw a tarrasque at the town and start fresh next time.
But seriously, I'm just at the research and tinkering stage. Addressing one problem at a time, and right now it's to do with valuing spell permanence and charges/recharging.
I'm all ears for any info on how to do that, or any insight into understanding how it was done for the official items in the books.