Will this house-rule method of choosing prepared spells unbalance the game?

Question

I have a party consisting of two PCs; a lv5 fighter (3 fighter, 1 rogue, 1 barbarian) , and a lv5 ranger (4 ranger, 1 cleric).

Focusing on the ranger for the purposes of this question. She doubles as our caster, and it's been working super well for us. However, we're feeling really hemmed in by the way prepared spells are managed in 5e. As a GM I don't like a) hounding her to pick spells after each long rest and b) limiting what they can do just because she didn't magically see into the future to realize Comprehend Languages would have been useful today.

I want to change how she prepares spells to allow her the roleplaying freedom to pick some spells at the time of casting, rather than needing to set them ahead of time. On the flip side I can see a lot of room for abuse so I'm considering offering one of the following two systems but would like someone to double check my logic (I'm a first-time GM and fairly unaware of what the later levels will bring.)

At this point her prepared spells work out like so;

She has access to eight spells total. Five are predetermined; three because she's a ranger and knows those spells, and two which are always prepared for her because of her cleric domain. This leaves three spells she must prepare at the beginning of each day.

I see two logical ways to resolve this.

Method 1

Of the three remaining prepared spells, one can be swapped at will at the cost of an action. The other two must be prepared ahead of time like normal.

IE, she can take a turn during combat to switch one spell for another spell of her choice (or prepare one if the slot was previously empty).

Needing to take an action to prepare the spell should be enough of a limiter to prevent abuse, and it gives her plenty of flexibility during combat. However, outside of combat it would logically follow that she can switch spells, at will, every 6 seconds. That seems pretty game breaking.

Method 2

The remaining prepared spells are empty until used. She can declare the use of a spell at any time for no penalty, but once the spell is declared she can't switch it again until the next long rest.

IE, over the course of a day she can select any three spells she likes to use but there's no option to change them once selected.

This feels more balanced between in-and-out of combat scenarios, but I can see it potentially getting out of control in later levels. I was thinking of restricting this down to just 1-2 "empty" prepared spells (the rest would be pre-prepared as usual) as a limitation if three is too broad.

TL;DR:

I want to give my player more flexibility in her prepared spells. Is one of these two methods more acceptably balanced than the other? Will it become unbalanced as she levels up?

Answer 1

While it's hard to judge balance, especially when it's not clear what you're balancing against, these two house-rules both have a pretty effective point of comparison... in an older edition.

In v3.5 of Dungeons & Dragons, Wizards had the option to something like what you suggest. They could opt to prepare only part of their spells and keep the rest open, so they could be filled in later. Wizards were considered one of the most ridiculously powerful and flexible classes in the game.

What you are proposing is even more powerful, because the Wizard at least required at least 15 minutes of rest to prepare a new spell in an open slot.

In my games, I've seen this feature used by a few players. (Most opted to just prep everything at the start of the day.) Here's what happened:

• Gameplay slowed down. Whenever my players would run into a problem that they could conceivably solve half an hour later, the Wizard would go down his spellbook and look for possible solutions that they could prep. Wizards tend to have a lot of spells in there, so this would take a while. Lots of banter would ensue over which spell the Wizard might prep. Half the time, in the end no spell was prepped and a different solution was chosen altogether.

• Players would look to the Wizard even more than normal. A Wizard who preps everything at the start of the day is incredibly flexible. A Wizard who can prep anything once you know what you're up against is just unreasonably flexible.

• The Wizard would ultimately stop using the feature because it's a huge mental load. As the spellbook grows, the number of things a Wizard could do in a given situations rises very rapidly. It was doable for a few levels, but it quickly became too much.

In the end, most players chose not to use the ability because it was both too good and too cumbersome. It would take too much table-time away from having fun and made a lot of encounters too easy.

You are likely to experience the same things as level goes up; the caster's options will go up rapidly, which increases their cognitive load and makes them much more powerful. If you think picking what to do in combat is bad when you have 5 spells to pick from, imagine how bad it gets when you have your entire spell list to chose from.

One of the reasons 5e cut down on how many spells you can cast at a given moment is because combat flows a bit more smoothly that way. And, like I said in my comment, there is a reward in actually thinking ahead now that you will lose. It's not your fault (or problem) that your players aren't gathering information about what they will be facing.

(As for hounding players to select spells; I always rule that after a long rest you prep the same spells as the day before unless you tell me you want to make changes. Most players have a default loadout that they use most of the time anyway).

Answer 2

My playgroup uses a house rule which is only a small change from RAW, and in my opinion is not too unbalancing. It's similar to your option two.

RAW indicate that preparing a spell takes one minute per spell level, and that you can change your list of spells after a long rest.

PHB Page 114, emphasis mine

You can change your list of prepared spells when you finish a long rest. 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.

And the other classes with prepared spellcasting all have similar entries. The house rule is that when you finish a long rest, your spells are "reset" and you can prepare some or all of them. If you prepare all of them, it's the same as RAW. If you only prepare some of them, you can prepare the remainder (or some subset of the remainder) any time before your next long rest - taking one minute per spell level of each prepared spell. This makes it useless in combat, which helps to preserve balance.

My suggestion for the spellcaster would be to leave one slot unprepared. That's what I usually do and I've rarely found it insufficient. Then if your party gets stuck in a desert and your caster wants to use Create or Destroy Water, she only needs to spend 1 minute preparing it. After that, if she followed my advice, all her spells are prepared and she has to wait until next long rest to change them again.

Answer 3

This sounds quite similar to ritual casting in 5e. I think that is quite well balanced: there is a restricted list of utility spells (like comprehend languages) that some classes can cast without preparing or using up a spell slot, but it takes 10 minutes to do so.

That means, any spells you need to rely on, you need to choose, but "interesting" spells don't get completely left behind because they're never the top priority to prepare.

It works differently for different spell-casting classes, notably for wizards. Rangers do not have the ability to do so, but they can take the ritual casting feat if they quality for it, or you could just decree that the character is balanced enough, if you give this as an extra bonus feat once, it wouldn't be a problem.

Answer 4

I still play D&D with people I learned with in 1980. Almost from day one our house rule has been that you can cast any spell you know (i.e. it's in your spell book, which it's assumed you routinely study). This is how we've been playing all these years, so I can vouch that game play remains balanced.

We've always used a mana point system: a fully rested spellcaster has mana points equal to character level * primary ability, e.g. a 10th level magic-user with INT 16 has 160 mana points. Casting a spell expends mana equal to the spell level squared (9 pts for a 3rd level spell, 25 pts for a 5th level spell, etc). A spellcaster recovers full mana after an 8-hour rest, half with 4 hours rest, or a quarter with 2 hours (the minimum useful resting time).

Even though this is how we've always played, I've always felt that it does skew the game a bit toward too much magic. That's okay in our group's case because we like magic. But I think this could be fixed by limiting daily spellcasting to the number of spells allowed in the standard rules, and simply allowing the caster to choose any spell known, within those level limits. This seems like a totally sensible thing - no other profession limits a person to using only a pre-planned set of skills or techniques. The idea of "forgetting" a spell has never made sense to me. But limitations on expending energy totally make sense.