It's a staple of the fantasy genre: faced with an obstacle the barbarian can't punch his way through, the wizard flips through his spellbook until he finds the perfect spell. He reaches into his component pouch, withdrawing—somehow—exactly what he needs, then casts a powerful spell, surprising the heroes and allowing them to continue on.

Wizards don't get to do that in 5e. They prepare so many spells per day out of their spellbook, and unless the other spells within are tagged ritual, they don't get to see use until after the next long rest.

I want to house-rule that a wizard can cast unprepared spells from their book in the absence of exigent conditions. If I have time and space to crack out my spellbook, being disallowed from mage armor, disguise self, or jump without [8 minus sleep] hours of study feels arbitrary. What about the game changes, especially balance-wise, if wizards are allowed to cast unprepared spells from their spellbooks?

Note: this would be different from [ritual] spell casting from the spell book. In this proposed scheme, casting an unprepared spell would still require slots.

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    \$\begingroup\$ Could you be more specific about how much time this would take? An extra 10 minutes, like rituals? \$\endgroup\$
    – Red Orca
    Commented Oct 17, 2020 at 20:03
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    \$\begingroup\$ Are you planning any penalties for having not prepared the spell? Are you considering similar house rules for non-wizard spellcasters (like clerics)? \$\endgroup\$
    – illustro
    Commented Oct 17, 2020 at 20:12
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    \$\begingroup\$ @Erik that's perfect actually. My real problem is that some spells are so niche I can't see why I'd ever prepare them, and the answers to that question--moreso than the question itself--are precisely what I'm looking for. \$\endgroup\$ Commented Oct 17, 2020 at 20:42

1 Answer 1


You'd be removing one of the most important limits on spellcasters.

Consider a few different spellcasting classes up through level 10 (after which the balancing mechanisms are similar but less straightforward):

  • Warlocks know about 1 spell per class level + 1, give or take (2-10 spells, and Patron spells are only added to the Warlock list, not necessarily known), and they can cast any of them 2x/short rest. They also get other stuff like Invocations and Pact benefits.
  • Clerics know all their class spells (16, 17, 25, 11, 16, for about 9 spells per class level depending on domain and sources), of which they can choose around level+4 to prepare, and cast (2, 3, 6, 7, 9, 10, 11, 12, 14, 15) = about 1.5 per level. They also get other stuff like armor or even weapon proficiencies, depending on domain. Druids work similarly, with either kickass Shapeshifting or extra spells.
  • Bards know just about level + 3 spells, and can cast one about 1.5x per level, like a Cleric. They also get a variety of bonus features, depending on subclass.
  • Sorcerors know exactly level+1 spells, and can cast them with spell slots like a Cleric. They get Sorcery Points, to use for extra spell slots or metamagic shenanigans, and relatively minor bonuses from their subclass.
  • Wizards know at least (2*level)+4 spells, probably more depending on the game. They can prepare about level+4 of them, and get nifty but modest benefits from their subclass.

Overall, the pattern is basically: every spellcasting class is limited in the amount of spell slots they have. They're also limited by either the spells they know, or the spells they can prepare. Technically, Wizards have both of these restrictions, but the number of spells they know is quite high, making the requirement to anticipate problems and prepare spells in advance the far more restrictive one on a daily basis.

And for all that, wizards don't get extra features as powerful as those of the Cleric, Druid, Bard, or Warlock. Why? Because wizard spells are deliberately more powerful. Wizards are the ones who bet everything on their magic, and the payoff is that they're overall better than other classes (except possibly the Sorceror) at doing damage, crowd control, defensive buffs, non-combat spells - basically everything except healing.

So if you let wizards cast from their spellbook, effectively removing the requirement to prepare spells, then you'd have an incredibly versatile caster who has the perfect spell for just about every occasion. Which could be a lot of fun, no doubt... but it'd probably make it a lot more difficult to spotlight the other players if the wizard can fix every problem on any given day. You'd have to really stress their spell slots before the other characters' usefulness became apparent, even more so than is already the case.

  • \$\begingroup\$ As a counterargument, I would offer that because clerics and druids have access to a wider range of spells to prepare (clerics access 33 at level 3, while wizards get 10 in their spellbook), and that because wizard class features are focused on spell augments where clerics and druids are focused on versatility, this makes wizards simultaneously the least versatile full casters while having access to the most niche spells. Wizards already have to choose what to take and leave when creating their spellbook; it still seems arbitrary--except for balance--to make them choose again in preparation. \$\endgroup\$ Commented Oct 17, 2020 at 21:13
  • \$\begingroup\$ That said, continuing arguments might well end up more philosophical than SE desires, and the question is closed anyway. I do appreciate the answer; it's reasonable and explains quite well a/the philosophy behind why RAW exists as it does, which is helpful to me. I still plan to ask my DM if I can go with Zeus' rule from the question this one duplicates. \$\endgroup\$ Commented Oct 17, 2020 at 21:17

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