My players in the Online campaign are interested in writing their own scrolls, and as I haven't written about magic creation on this blog before, I'd best do so now.
This is my solution to the problem of scroll creation - it addresses no other magic. I should probably write those rules at a later time. First, I want to say something about the possession of magic by players.
I don't feel excessive magic does anything for the game. What would "excessive" be? If the players are solving more than a fifth of their problems with the use of a magic item, then there's too much magic. I don't mind the occasional use of a fireball wand or such - but the players should be aware that there isn't another fireball wand waiting in the next treasure. That sucker should be precious ... and therefore, not to be used until the player's backs really are against the wall.
If you're running a world where the fireball wand is the first thing the mage uses, that is a sign that you are giving your player too much magic. Why? Because they don't need to think, that's why. They don't need to be careful. They have their deux ex machina in hand, and the dramatic relevance of your world is suspect. Of course, if you just want to run a bunch of people slaughtering things, without experiencing real threat, that's fine ... but you and your buddies are morons, and you have no business reading this blog.
I like the party to have magic. My parties soon learn that magic cannot be bought, and that if they cannot find it, they'll have to make do without. Even when they do find it, knowing it may not get replaced at once tends to make parties appreciate magic. Thus, when considering the creation of scrolls by mages, difficulty has to be the watchword.
Not all casters should be able to create all scrolls. The higher the mage, the easier it should be ... but every level of spell requires new challenges, and while an 8th level caster may have little trouble with 1st level spells, 4th level spells should be a considerable challenge, and 7th level spells impossible.
I like a base % chance of success. This is equal to the caster's level above that needed to cast the spell, multiplied by either the caster's wisdom or intelligence. Thus, a 4th level mage with a 17 intelligence would have a 51% success chance to create a 1st level scroll, and a 17% chance to create a 2nd level scroll. Mage and Illusionist cantrips are considered zero-level for the purpose of this calculation.
To have any real chance of scroll creation, the caster would need to obtain three rare books - none of them unique, but somewhat difficult to find. They would be large, 14 in. high and 10 in. wide, with around 480 pages, costing upwards of 1,000 g.p. They would be massive tomes, which would be made of delicate parchment, sensitive to damp and dryness, and therefore difficult to transport. I conceived of these books last night, and I think they would begin a whole list of books I'd like to eventually add to my Printer's equipment list. The rarity would mean that the three books were hard to find, and once found, hard to replace. The titles would be,
Tobin's Materials & Measures - including the list of what was needed, how to recognize good material from bad, and what considerations must be noted depending on the time of year and location of the effort. Thus, without this book, a caster would likely choose the wrong toad's liver for the spell, or pick a sparrow's wing that had lost its potency, for failing to know what is it that makes a good pick.
Six Degrees of Ink: A Master Mixer's Manual - there's more to using magical ink in a scroll than purchasing a bottle at the apothecary's. Inks must be mixed and managed according to precise specifications, depending on the spell and the quality of paper - which itself can ruin a good scroll. Here are the rules to choosing how to remix ink in order to precisely create the results a caster desires.
Leomund's Incantations of the Written Word: Unexpigated - a thousand symbols, chants, guidelines and methodologies for infusing the spoken word into permanent written form, in order to freeze magic so that any able to verbalize the written word thereafter can release it into the world. If the spell is to work when anyone reads it, there must be a code that is followed, or the power of the spell is locked into the word so that it cannot be released.
A caster could create scrolls without the above books, but for calculating success the caster's intelligence or wisdom is reduced 4 points for every book not possessed. Thus, a mage with a 17 intelligence who possesed only Leomund's Incantations would have a 9% chance per level of success. Still possible, but the difficulty of remembering so many details would make the matter less likely.
This brings us to the ingredients, and the means to manage the ingredients. I don't insist on mages using "material components" in casting spells ... but said components are convenient for scroll creation. I have included some spell components in my Apothecaries' list, pricing the described items in the Player's handbook. Every material component that was to be used would require a metal cage for living items, a bowl for liquids (wooden if harmless to consume, metal if otherwise) and a glass container for anything either animal, vegetable or mineral. A glass rod would also be required for each item, a mortar and pestle, a brazier, chalk and paint for drawing symbols (one oz. per spell level), a blank scroll of parchment 12 in. wide and 14 in. long (per spell level), plus 2 ounces of magical ink (per spell level).
I may add more to this at a later time. For now it seems an adequate description.
The actual writing of the scroll will require 1 week per spell level, which must be accomplished in a completely quiet and undisturbed place, indoors, where there is both natural light and continued provided light (a candle or torch or lantern per spell level must be kept burning continuously). The caster cannot pause to cast other spells during this time, nor can he or she take time to investigate other matters, leaving the scroll creation to wait. Others must be on hand to keep candles or otherwise lit and provide food, and an apprentice must be on hand to keep materials clean and rid the laboratory of the smallest vermin that might ruin the creation. Excessive noise, such as a battle or even someone shouting, increases the chance of failure by 1% per round of distraction.
Only when all this has been managed is the chance for success rolled ... and if it fails, all material components, paper and ink have been ruined.