Assign every scroll and spellbook a random “writing difficulty” value at the start of the game. Say it’s stored as a percentage chance (in reality, this is an implementation detail and could differ). Every time you attempt to write a scroll or book, it computes your own percentage chance to correctly write something unknown, which is deterministic and only depends on stats like Luck and Intelligence and your role. Whether you write the scroll successfully or not depends on whether your computed percentage beats the randomized percentage of that scroll.

For each scroll and spellbook you try to write in the game, resolve the random writing chance exactly once, the first time you try to write it when unknown. If that initial attempt fails, mark the scroll or spellbook as not knowing how to write it, so that subsequent attempts will fail with a message like “You don’t know how to write that, so you don’t even try to.” which means they won’t eat up ink either. If you subsequently learn the identity of the scroll or book, you become able to always write it successfully as normal.

Scrolls can be “corrupted” or “misspelled”. This basically acts as a toggle on whether the confused behavior of the scroll activates: reading a corrupted scroll while not confused will produce the confused effect and reading it while confused will produce the regular effect. There is no way to restore a corrupted scroll to normal.

Possibly, an unidentified corrupted scroll will have its label deterministically garbled similar to engravings, e.g. “scroll labeled FO0B|E BLe7Ch”. If identified it would simply show as “corrupted scroll of X”.

Writing a scroll while confused will make the result corrupted. Also, scrolls hit by water damage or produced from polymorphing other scrolls may be corrupted.

If you attempt to write enchant weapon or enchant armor (that you already know the appearance of) while confused, you will instead write the other one, even if you don’t yet have it identified.

If you attempt to write something using a marker which dries out in the process, you can continue writing by switching to another non-dry marker you have in your inventory. If you don’t have another one, or decline to use another one, you get the same dry-marker effects that happen now.

One possible failure effect for reading a spellbook (or writing it, if it’s possible to fail at writing a book) is for the spell to force itself into your head. Your spell retention is internally -1, a special value that means you can cast the spell, but only once, and then you immediately forget it.

Add “magical writing” as a nonweapon skill, which is trained at a fast rate by writing scrolls and spellbooks, and increases your odds of writing unknown scrolls and spellbooks successfully.

Artifact magic marker Scrivener. It generates with 3 charges and cannot be recharged. Instead of using the charges normally, a single charge will write any scroll or spellbook without fail.

The chance for writing an unknown scroll or spellbook is based not on luck but on how many scrolls and spellbooks you already have identified (and thus, how familiar you are with their sort of magic).

This was later written up as a more complete proposal.

Failing to write an unknown scroll or spellbook just consumes an average amount of ink; otherwise it implies that the character knew how much ink the job would have taken.

Spellbooks cannot be written by appearance. If you don’t know the spell, you can’t unknown-ID write it based on appearance (though you can still try to make an attempt to write it based on the spell).

Writing an unknown spellbook is not as likely to fail outright as it is now. Instead, there is a chance that it will “warp strangely” as normal, and become some ‘‘other’’ spellbook you don’t know yet.

Desks as dungeon furniture: they can store items like a container, and acts like a table if you are on top of it (if levitating you can interact with it and things on it). Sometimes generates a magic marker inside. Writing scrolls or spellbooks at a desk has some bonus: maybe a higher chance of writing unidentified, or a slightly reduced or capped ink cost. Possibly put one or more in the College of Archaeology, and Warden Arianna’s office for Convicts.

You can write a scroll onto a piece of paper armor (with a magic marker, incurring the regular ink cost), then instantly read it.

Writing “Elbereth” in the prompt for writing a scroll should alias to “scare monster”.

The hero can either not write unknown scrolls and spellbooks at all (writing by appearance is still fine as long as the appearance is known), or else the chance of writing one increases with every scroll and spellbook the hero identifies.

See also this proposal which expands on the idea.

In variants with felt markers, allow them to write spellbooks and scrolls of mail - the other scrolls are the only thing they can’t write.

Your success chance of writing an unknown scroll or spellbook should be based on Intelligence, not Luck.

When you fail to write a scroll because you ran out of ink, it will become a “garbled scroll” instead of disappearing. Garbled scrolls can’t be read (or possibly they could be read, for a number of generally negative weak magical effects), but they can be re-blanked so the scroll can be written again. This could also happen when you fail to write a scroll by not knowing it. There is a slim chance, probably less than 10%, that you end up writing some random scroll instead of a garbled scroll.