Pricing a homebrew magical item allowing the use of a random spell

Question

Most of my players are magic users, so I created a homebrew wondrous magic item that I hope they will find slightly useful and mostly enjoyable for many game sessions to come (they are mostly level 6 or 7). I know how to figure out most properties of the item, but I would like to know how to figure out the price.

Here's the item:

Novel of Syntactical Magical Novelties

This small leatherbound and shabby-looking booklet contains one dozen worn and torn yellow pages with random scribbles on them that don’t seem to make any sense to the casual observer. Upon examination, magical writings appear to be hidden amongst the scribbles.

The booklet always contains exactly one spell attuned to the owners magical preference and usable directly from the booklet once a day by the owner without requiring any spell slot. The spell is always a syntactically incorrect version of an existing spell and modified to behave accordingly (for example, Wind of Guts instead of Gust of Wind might add a nauseating effect). Casting a spell from the booklet requires the owner to be familiar with the spell and requires perusing the booklet which results in a full round of casting in addition to the normal casting time of the spell. The spell cannot be memorized or copied out of the book in any way and is replaced with a new spell at the start of each game session (by the DM). Transfer of ownership of the booklet won’t be honored until the next game session (the booklet, its contents and its limitations on daily use remain unaffected).

Caster Level is probably 17th because I haven't included an upper limit on the spell that could be in the booklet (although if I would also allow metamagic Caster Level is probably even higher?). Price probably varies? I have no clue how to assess that because almost any (metamagically enhanced) spell could be in the booklet (as long as it fits on 12 pages). or should I maybe consider pricing it as a regular 12 page booklet because to most common shopkeepers it will probably seem useless?

PS: I'm only interested in the sales price; item creation price doesn't bother me because I won't allow any copies of the book.

Answer 1

The item as listed is on par with another pre-existing Artifact. You will need to lower its abilities to be able to generate a price.

The item as written is a modified version of another 3.5 item called The Book of Infinite Spells, which is an artifact-level item. Your version is actually more powerful as it does not disappear, and the spells are tailored to the class of the user.

As an artifact it's technically priceless. This makes assigning a value subject to things like favors, and entire quests or entire kingdoms - that sort of thing.

Alternatively, you could do something based off the shadow spells:

• Shadow Conjuration
• Greater Shadow Conjuration
• Shadow Evocation
• Greater Shadow Evocation

Usable once per day, you can have a magic item that mimics those spells, but makes them the actual spell. The kicker here is that since there is a more limited scope (spells of a specific school that are of x level or below), it will be easier to reference and create what you're looking for.

Another reference point is the wish and limited wish spells, specifically the spell duplication aspect of the spell. "As limited wish, but only in regards to duplicating other existing spells of x level or below" kind of thing.

Have them select the spell they want prepared, and it takes 8 hours to sift through all the pages to reset the page to a new spell.

Conclusion

As written you've created something more powerful and usable than a pre-existing artifact. As such it is "Priceless". Tone it down using existing spells like shadow evocation or limited wish to price it using the standard DMG guide.

Answer 2

The novel's priceless… to a magic merchant or researcher

The recommended way to determine initially an original magic item's price is by comparing it to existing magic items. Unfortunately, as this fine answer mentions, the closest thing to the novel of novelties is the book of infinite spells (Dungeon Master's Guide 277) (artifact; 3 lbs.), and, as an artifact, the book can be sold for whatever someone will pay for it—if it can be sold at all! (Some folks won't touch artifacts—literally and metaphorically—as they tend to attract the wrong kind of attention and often bring with them significant drawbacks or even curses.)

Thus the same should apply to the novel. While it's certainly a minor artifact given the strict limitations on who can use it, how often it can be used, and—most despicably and what will cause the PCs to want to sell it—how long it takes to cast a spell from it, the novel remains a potentially endless source of previously unknown spells, and that's an immense boon to magic research… even if those spells have silly names. That is, because those spells in the novel exist at all, it should be possible for a caster in possession of the novel who's willing to research original spells to develop a spell like one that was once found in the novel into a normal spell that can be prepared and cast traditionally, the researcher having been given a leg up in that he knows before the research begins that the spell's viable because the spell already existed! (See Researching Original Spells (DMG 198) and this question.)

Beyond this, while "[t]he spell [in the novel] cannot be memorized [i.e. prepared] or copied out of the book in any way," effects from magic items can be used to create other magic items. So, for instance, if the novel currently displays the 1st-level Sor/Wiz spell Tenser's doting fish (it's like the unseen servant spell but smells bad), and novel's owner can find someone with the feat Craft Wand (Player's Handbook 93), together in one day they can use the novel's spell to create a wand of Tenser's doting fish; doing so costs 375 gp and 30 XP. Then, using that wand of Tenser's doting fish the owner can, with the help of the feat Scribe Scroll (PH 99-100), create scrolls of Tenser's doting fish, copy the spell into his spellbook and also spread the knowledge of the fish spell far and wide.

This is a thing, and it's difficult to stop. While I don't expect all players to be like my players, I'd quickly tire of each session creating a new, carefully balanced spell… especially if the spell was intended solely as a joke. That's because my players would, I'm sure, initially find the novel's spells funny, but then they'd carefully examine the spell and attempt to add it to the campaign before it disappeared, and the spell wouldn't be a joke anymore: They'd be just spells, forevermore added to the campaign having been found once in the novel.

I understand the desire to have funny spells in the campaign, but I recommend first putting a couple of funny spells on scrolls, gauging the players' reactions and the amount of time it takes you to create the spells (you are, by the way, the most important factor here—the novel of novelties, as written, makes more work for you when you already have enough to do!), and, then, if everybody loves the idea, consider introducing a minor artifact like the novel.