How does adding Spells Known and Spell Slots work?

Question

I am struggling to understand how exactly a player learns new spells, let's take for example the Ranger class:

• At level one they don't get any spell or cantrips.
• At level two they get to learn 2 spells with level 1 slots available.
• At level three it says they know 3 spells with level 1 slots available.

Does that mean that at level 3 they know 3 spells of level 1 or are they added to the spell pool of previous levels, so 2 + 3 = 5 spells known in total at level 3?

Can someone please explain this as thoroughly as possible and, if needed, use examples from other spellcasting classes like the wizard and sorcerer as well.

I've looked in chapter 10 and 11 of PHB but haven't found the answer.

Answer 1

Casting spells is different from knowing/preparing spells. The only connection is that when you cast a spell, it must be from those you know or have prepared (with limited exceptions for some rituals). There are 3 tables for how many spellslots a character has to cast with -- 1 for full spellcasters (wizard, cleric, bard, druid, sorcerer), 1 for half casters (rangers and paladins), and 1 for third casters (eldritch knights and arcane tricksters). Warlocks have a different system for this.

Know or preparing spells is different.

Wizards, clerics, druids, and paladins prepare spells -- each has a number of spells they can prepare, and can change them after a long rest. On that day, they can only cast those spells, using their spellslots to do so. Clerics, druids, and paladins choose the spells they have prepared for the day from the entire list of spells; wizards choose from those they have in their spellbooks.

Bards, rangers, warlocks, sorcerers, arcane tricksters, and eldritch knights are much more limited in spell selection. For each of these classes, in their class table it says how many spells the character may know at any given level. When they go up a level, they check that table to see if the number of spells they know goes up; if so, they pick a new spell (or spells if it goes up by more than one) to add. At leveling up, they also have the option to change one spell they know to a new one that they can cast.

When the spellcaster casts a spell, this does not in any way affect which spells he knows or has prepared. Those do not change with casting; each time he casts a spell, he can cast any spell that he knows or has prepared, using a spell slot equal to or greater than the level of the spell he chooses to cast.

So, to answer your request for examples:

A 5th level ranger knows 4 spells. He has just gained the ability to cast 2nd level spells, so he can at most know 2 of those (one for the spell he gained at 5th level, and one could be changed from one of the 1st level spells he knew previously). The other 2 spells he knows will be 1st level spells. He has 4 1st level and 2 2nd level spell slots with which to cast those spells he knows.

A 5th level paladin can prepare a number of spells equal to his charisma modifier, plus 2 for his level. So, for example, if the paladin has a 16 charisma, his modifier is +3, and so at 5th level he can prepare 5 spells. After each long rest, he either keeps the spells he has prepared, or spends a few minutes preparing a different set, from the paladin spell list. He can prepare 1st and 2nd level spells (since that is what he is able to cast), in any combination. He has 4 1st level and 2 2nd level spell slots with which to cast those spells he has prepared.

Answer 2

So, spells known versus spell slots is your first confusion. When you learn spells, slots don’t come into play at all—learning a spell just takes up a “spell known,” rather than going into a “spell slot.”

Spell slots, rather, are what you use to cast spells each day. So when you cast a spell, you use a spell slot. Cast it three times? Use three spell slots. Your spell slots refresh each day.

As for reading the spells known table, or really pretty much any level-based table in the book, the numbers you see are your total at that level. So at 3rd level, that ranger has 3 spells known total, not 3 more than he did at 2nd level for a total of 5. That way when you create a character at higher levels, you can just read the total off the table, instead of having to add up all the previous levels.

So can you tell me how much spells in TOTAL does a level 5 ranger and a level 5 paladin know ? – Drunken Commoner 2018-03-24 13:36:33Z

A 5th-level ranger knows 4 spells, because 4 is the number listed in the Spells Known column at 5th level in the “The Ranger” table on Player’s Handbook page 90. You do not need to add up the previous entries in that column. Note that in regular play starting at 1st, a ranger would be restricted in what level of spell she could learn as she levels, and the Spells Known of 1st Level and Higher section on page 91-92 concludes with a paragraph explaining how you have to simulate that if creating a 5th-level ranger from scratch (which basically ends up meaning that only two of the four spells you know can be 2nd level, the others have to be 1st).

A 5th-level paladin doesn’t “know” any spells, or alternatively, “knows” every paladin spell ever, depending on how you want to look at it. Unlike the ranger, who has to decide to learn specific spells that will be hers for the rest of her life, the paladin prepares spells each morning, and they can be different spells every day. The number of spells he can prepare each morning is given on page 84 as “equal to your Charisma modifier + half your paladin level, rounded down,” so at 5th level that’s going to be 2 + Cha, whatever your Cha modifier is.

Answer 3

For most spellcasters, you can find the number of spells known at the level in the class table, not the number of spells they learn. For example the sorcerer:

The Spells Known column of the Sorcerer table shows when you learn more sorcerer spells of your choice. Each of these spells must be of a level for which you have spell slots. For instance, when you reach 3rd level in this c1ass, you can learn one new spell of 1st or 2nd level. (PHB 101)

You learn one spell at 3rd level, not 4.

Wizards work a bit differently, as they add spells to their books and not "learn" them:

Each time you gain a wizard level, you can add two wizard spells of your choice to your spellbook. (PHB 114)

And divine casters (clerics, druids and paladins) do not learn spells at all, they only prepare them and can choose any from their list that they can cast.