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Some of the feats in D&D 5e are seemingly less useful or otherwise not always as reliable relative to the other feats, although they are very flavorful. Keen Mind is one such feat, granting your character a 30-day eidetic memory, master navigator, and time keeper.

However, there can be workarounds for the last two benefits (benevolent DM, hand waving, finding NPCs who know the area, etc), and the first benefit does not seem to have an everyday usefulness to shortlist this feat for a wizard -- not over War Caster, Resilient(Con), Alert, or Tough, for example.

At best, people seem to think it's just a way to make the DM rehash their old hints if you missed them the first time.

Here is the text for Keen Mind:

Keen Mind

You have a mind that can track time, direction, and detail with uncanny precision. You gain the following benefits.

  • Increase your Intelligence score by 1, to a maximum of 20.
  • You always know which way is north.
  • You always know the number of hours left before the next sunrise or sunset.
  • You can accurately recall anything you have seen or heard within the past month.

If you're a wizard, you will be reading your spellbook everyday. It is within the bounds of the feat to say you recall absolutely every glyph, symbol, and diagram of your spellbook, down to the ink stains and page number of each word of each spell.

One cool way to make use of Keen Mind is to make the spellbook obsolete -- within the DM's approvals/restrictions.

Here are things a wizard can do because of their spellbook:

  • They can change their prepared spells after a long rest
  • They can scribe new spells upon gaining Wizard levels
  • They can cast rituals without expending spell slots
  • They can use Arcane Recovery
  • They can gain Spell Mastery or Signature Spell if they have the spellbook upon leveling up

If the wizard has the spellbook engraved in their mind, which of these things can the wizard still do, and which can they no longer do, if that same wizard did not have a spellbook at hand for some reason?

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Note that your premise has an error, as you cannot gain the other benefits of Keen Mind easily by in-game means: there is no compass in the 5e equipment lists (personal compasses are a post-medieval technology); hour glasses don't work that way (they are timers not clocks); and making and using a map means you lose your Passive Perception score (PHB, p. 183). Keen Mind has a lot of benefits in games where the GM is being impartial about information access and not giving it away for free. – SevenSidedDie Mar 16 at 18:01
@SevenSidedDie Good catch with the compass and map. I mentioned hourglasses because you could still technically track time with it, if you had a large/numerous enough hourglass that causes sand to fall slowly enough (essentially a 12-hour timer). It would not be convenient. Still, even then, one would probably still pass Keen Mind up for the other feats I mentioned for combat effectiveness. – markovchain Mar 16 at 18:52
Depends on whether the Combat pillar is being promoted over the Exporation and Roleplay pillars or not. But regardless: the question asked is plenty interesting and useful. :) – SevenSidedDie Mar 16 at 19:17
@SevenSidedDie Conner's A People's History of Science (2005) gives an excellent chapter or two on the (not-trivial) development of proper clocks that can be used at sea, and different navigational technologies where there is no compass. This material is ripe for those doing world-building and wanting to understand society/technology relationships, in addition to being a fabulous history bok in general. :) – Lexible Mar 16 at 19:48
@markovchain 2 things: 1) you can also create a copy of your spellbook at a reduced cost (1 hour & 10 gold per spell level to scribe a spell vs. 2 hours & 50 gold per spell level); 2) assuming that your wizard has no spell book with them at the end of the month they lose any spells stored in their head aside from prepared ones – name moniker Mar 17 at 0:41
up vote 23 down vote accepted

Things you can do, by the book: Everything you listed except scribe a new spell.

Source: PHB pg. 114

That actually requires you to write down the spell, and has a material cost associated with it that is usually associated with special inks and gems. Yes, you can recall it from memory and write it into your book, upon which you would have it memorized for a month. However the spell itself may require a specific rune written in a specific ink. Knowing that, and having written it down that way are two different things. Obviously this applies to material component cost spells only.

Since the Wizard can already replace a destroyed spell book with the spells he has prepared for the day, it's reasonable to extrapolate that with photographic memory (as this feat entails) you could replace the entire book. After all, the spells don't disappear from your mind when you cast them, so this feat should serve as a good safeguard against losing your spellbook.

Of note: You're going to want to review your book monthly and update it with new spells in order to continuously preserve this.

Of secondary note: I would even allow a Wizard with this feat who passed a successful Arcana check to experiment with and replicate a spell cast by somebody he was watching. Personal DC levels would be, DC +5 per component needed (Verbal, Somatic and Material), and double the result if the Wizard isn't proficient in Arcana. But that's a house rule thing because this is a clever use of a versatile feat that effectively duplicates the spell book.

But bottom line is: Nothing under Wizard or the Spell Book sections in the PHB prevent you from recalling everything in your book from memory. The pertinent line is here:

Preparing a new list of wizard spells requires time spent studying your spellbook and memorizing the incantations and gestures you must make to cast the spell: at least 1 minute per spell level for each spell on your list.

Since Keen Mind already ensures you have the spells memorized, there`s no reason you would need to open the book in order to review them.

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+1 That is a fun homebrew. It would need DM approval definitely, but it certainly makes sense in the context of the feat. Flavor like this makes the RP fun, and perhaps even puts it on par with Alert or War Caster with the homebrew IMO. – markovchain Mar 16 at 17:31

TL;DR: Keen Memory can't replace the magic on the spellbook.

Disclaimer: This answer is based on the premise that there is something inherently magical about the spellbook or the ritual of preparing spells. GM should rule about it and, if it fits with how magic is handled in your campaign, everything is possible.

The spellbook is more than just a book with your spells written on it. The book itself doesn't have to be magical, but the ink with which you write spells may be (10 gp per spell level is a lot for normal ink) and it takes a lot of time to write them (1 hour per spell level). This indicates that there is more than words on it.

Transcribing spells isn't a copy/paste process, it's a ritual that embeds the magic into the book, and memorizing spells isn't just remembering the motions, it's engraving the magic on the wizard's mind.

Even a wizard with the worst memory could remember how to cast magic missiles after casting it every day for 30 years, but still needs the magic in the spellbook to burn the spell on their mind, the same way they can project the spells burnt in their mind into a different spellbook.

Asuming now that there is something other than memory that is needed to prepare spells, the feat won't be able to substitute it. If not, then you should only need to refresh the spells once each month.

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Yes, I forgot the book itself could be anything, but the cost of writing spells on it (10 gp and 1 hour per spell for your own, without needing to decipher someone else's "code") proves there is something else there than just words and diagrams. – Santreim Mar 16 at 16:28
Savants have deep experience on a specific school of magic. That might mean as you say, or that something works different on their brain, and need less magic to trigger the spell on their brains. And if, as you say, a spellbook is just a book without anything special or magical, materials aren't more than just ink if you don't have to decipher and try it out, just ink. How can you justify such expensive ink? 10gp is 1 ounce of normal ink. That is a lot of ink, even for a lvl 1 spell – Santreim Mar 16 at 16:44
The rules do not say the ink is magical. They specify the inks are "fine" which can suggest why they cost so much, but it can go either way. To impose the inks are magical is homebrew. See:…. Anyway, so to answer my question, to what extent do you think can Keen Mind replace the spellbook? Your answer is specific to transcribing spells, what about the other features? – markovchain Mar 16 at 17:01
That's the key, I use the transcribing as an example. Anything magical based on the power of the spellbook can't be done just with memory. If you consider the spellbook is just a list of notes, then follow Lino Frank Ciaralli's answer. But take care this is a buff of a feat, so it probably won't work strictly by RAW – Santreim Mar 16 at 18:42
Fair enough, the crux here I think is not if the ink is magical (which I think it's not from strict RAW), but whether or not a proper physical spellcasting book is somehow a requirement of the magic. From the answers we have, I'd say it's not clear by RAW and so has to be a DM ruling, may change table to table. On that vein, I would say it is not necessarily a buff of a feat. – markovchain Mar 16 at 19:04


You asked what if a Keen Mind doesn't have a spellbook. By the book, the Keen Mind feat doesn't mitigate not having a spellbook, and so the Keen Mind can't do any of the items on your list.

Is Keen Mind mechanically useless?

You imply that Keen Mind is mechanically useless. Certainly in a particular situation a particular feat could be mechanically useless, but that does not necessarily apply across the board. The points listed in Keen Mind could be quite valuable. For instance, it would make it nearly impossible to get lost underground. In some campaigns that would be a serious advantage.

Does Keen Mind replace the spellbook?

You say it is within the bounds of the feat that Keen Mind could replace a physical spellbook. It is not within bounds of a by-the-rules reading of Keen Mind, because at a minimum:

  • There is a mystical component to memorizing spells, that Keen Mind does not address at all
  • Spellbooks require special ink, which says that there is something about the spellbook that is more than just the information
  • There could be more to a spellbook than spells you've memorized in the last month
  • Transcribing a spell from a spell scroll destroys the spell on the spell scroll, which implies there is something beyond memorizable information within the spell

Is a Spellbook Merely Paper and Ink?

A spellbook is not merely paper and ink, or merely rote memorization. It is somehow integral with how wizards access the source of magic. While not spelled out in so many words, it is implied by the rules:

  • Other classes access the same spells without a spellbook
  • Spell slots are recovered with Arcane Recovery, implying that use somehow removes the spell from the wizard's mind
  • The ink is "fine" in some way, implying that somehow the quality of the ink is important

All of this implies that there is something important about the process of the spellbook beyond mere memorization.

What you're suggesting is an interesting homerule

It's a cool idea. Another way to get there might be a completely homebrewed feat called, for instance, Spellbook of the Mind, which grants the abilities you're discussing. That might be really cool. Might need to cost 2 attribute points, too, since it does away with a class limitation.

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The mystical component is shown in that wizards and other classes access the spells through different mechanisms. Maybe "mystical" isn't the right word, but there is a special sauce, and the buff of Keen Mind does away with that. – Jack Mar 16 at 21:10
A cleric without a deity or warlock without a patron is a wizard. They use magic not via another being, but by manipulating it directly themselves. Anyway, your reply suggests your answer is not a by-the-rules reading either (until you can produce a passage from the PHB at least). Can you change your answer to reflect that? – markovchain Mar 16 at 21:17
@markovchain Given that almost every sentence of the wizard's preparation includes the word spellbook, asking for quotes seems a bit ingenuous. – Miniman Mar 16 at 21:32
@Miniman That's true. Sorry, I was genuinely looking forward to a passage that supported the three bulleted points Jack put forward (the mystic component, the ink component, the "other" component). That the rules mention "spellbook" and the question being to what extent can perfect memory replace a spellbook, is why I did not consider your particular point. That said, point noted. – markovchain Mar 16 at 21:38
@markovchain - I've updated the answer, but there is no direct quote supporting my position, just is there is no direct quote supporting your position. In the end, Keen Mind doesn't say "therefore wizards don't need a spellbook". A GM can make a homerule that says that's what it implies, or make a new feat that says "a wizard doesn't need a spellbook, but the feat doesn't say it. – Jack Mar 16 at 22:07

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