D&D 5E Spellcasting Rules Explained In A Way That Actually Makes F**king Sense
“What is a Spell Slot? Spells have levels, right? Are they the same as Spell Slot levels? How many spells do I know? Do I have to prepare spells? What the actual f**k is going on?”
Author Note: Oh man, this article is nearly two years old and still being found! As of 19/01/2020 I’ve made some minor amends — mostly typos, some minor rule corrections (the irony of this article having rules errors in it is not lost on me, but does highlight the need for itself) and addressing some reader comments. Thanks to all for reading and sharing. You can find more of my work on my Itch.io page, or follow me on Twitter.
If there is one thing that crops up all the time with new people learning D&D, it’s that the rules around spell casting are just super hard to “get”.
It’s great that different classes that cast magic do so in different ways, as it allows for an awesome variety in both flavour and mechanics. But hot damn the PHB’s rules for magic are spread just a touch all over the place, and so I seem to spend my entire life explaining the rules of magic to new players.
So, lets explain it once and for all. Step by step, with examples.
I’m gonna start with the rules that apply to all classes, and get more specific from there. So, Spell Slots. Let’s do this.
“First and foremost; the f**k is a Spell Slot?”
A Spell Slot is D&D 5E’s mechanism through which a spell is cast. Think of a given Spell Slot as being like a barrel of a revolver — every time you cast a spell, you “use up” a Spell Slot, and you (usually) get all your Spell Slots back every time you take a Long Rest. Each class gets a number of Spells Slots to use per day.
Both spells and Spell Slots have levels. This is going to be a major point of confusion, so read on carefully! When it comes time to cast a spell, you use up a Spell Slot that is the same level as the spell or higher.
For example: your character has two 1st level Spell Slots, and one 2nd level Spell Slot. You want to cast Burning Hands, a 1st level Spell. You can expend (“use up”) one of those 1st level Spell Slots OR your 2nd level Spell Slot in order to cast Burning Hands through that slot. Easy!
“Why would I want to use my 2nd level Spell Slot in order to cast a 1st level spell? Surely I should save that to cast a 2nd level spell?” — you, totally justifiably.
You’re absolutely right! However, there are a couple of reasons you might want to use a Spell Slot of a higher level than the spell itself.
- maybe you’ve used up all your Spell Slots of the same level for the day, but you still really wanna cast that spell.
- some spells become more powerful when used in a Spell Slot higher than their own level. Think of it as like “charging up” a spell by “firing it through” a higher level slot.
Every class has a number of Spell Slots per day based on their level. For example, a 4th level Druid has four 1st level Spell Slots, and two 2nd level Spell Slots. The more Spell Slots, the more spells you can cast before needing to rest and recover your expended Spell Slots.
Finally, finally, one last thing to note — characters also have levels. I know you know this. But, and say it out loud with me; “my character level is NOT my spell level or Spell Slot level”. The designers of D&D have a serious problem when it comes to the word “level”, so I wanted to clear that up before we go on.
OK, everyone understand Spell Slots? Sick. Let’s move on — knowing spells.
“How many spells do I know?”
It depends. Some classes know all of their spells. They don’t have any concept of having to learn new spells. A class like this is the Druid — a Druid never needs to actively learn new spells. When it comes time for these classes to prepare (more on this soon) or cast their spells, the entire pool of their class spells is available for them to work with.
On the other hand, other classes do need to explicitly learn new spells. An example of this is a Wizard — Wizard’s have their spellbook, and they can only work with spells that they know. Another example would be the Sorcerer — though they don’t have a spellbook, they do have a limited number of spells that they know. When it comes time for these classes to prepare or cast their spells, they work from this list of known spells, instead of all their class spells.
For those classes which explicitly do learn new spells each level, the actual process is easy: simply consult the PHB and choose which new spells you want to learn from your classes spell list.
More examples!
Bill is playing Wraxan, a 3rd level Sorcerer.
At 1st Level (when Bill made Wraxan), Wraxan knew two 1st level spells. Bill chose:
Burning Hands (A 1st level Spell)
Mage Armour (A 1st level Spell)
When Wraxan hit 2nd Level, he knew 3 spells. As he still only had access to 1st Level Spell slots (and therefore could only learn 1st Level Spells), Bill chose Witch Bolt (A 1st Level Spell).
As Wraxan hit 3rd level, he gained his first two 2nd level Spell Slots, and he knew 4 spells in total. This means Bill could have chosen another 1st level Spell for Wraxan to learn if he wanted, or his first 2nd level Spell. He decided to go for a 2nd Level Spell, and Wraxan learned Scorching Ray (A 2nd Level Spell).
So, as it stands, Wraxan knows the following spells:
Burning Hands (A 1st Level Spell)
Mage Armour (A 1st Level Spell)
Witch Bolt (A 1st Level Spell)
Scorching Ray (A 2nd Level Spell)
As a 3rd level Sorcerer, Wraxan has four 1st level Spell Slots, and two 2nd level Spell Slots. Therefore, a day of spell casting for Wraxan could look like any one of the following:
- he ends up needing to cast Burning Hands a whole bunch (hey, Goblins don’t cook themselves). He casts it three times using three 1st Level Spell Slots, then twice more using his two 2nd Level Spell Slots (as Burning Hands gets a nice bonus when cast with a higher level Spell Slot) then finally one more time with his last 1st level Spell Slot. Goblins cooked, he takes a long rest, and gets all his Spell Slots back.
- he casts Burning Hands, Mage Armour, and Witch Bolt once each, all with 1st level Spell Slots. He ends up not needing to cast any more magic that day. He takes a long rest, and gets all his Spell Slots back in the morning.
- he casts Scorching Ray twice, using up both his 2nd level Spell Slots. He wants to cast Scorching Ray another time (Goblins don’t scorch themselves either, OK?) but is out of 2nd level Spell Slots! So he casts Burning Hands instead (as he hasn’t used any of his 1st level Spell Slots yet).
Your class most likely has its own, specific rules regarding how you learn new spells. For example;
- Sorcerers learn new spells when they level up.
- Rangers learn new spells every other time they level up (odd levels specifically).
- Wizards learn spells when they level up or by copying spells into their spell book, in the game.
- Bards have a “maximum number of spells known” that increases as they level up, and they can replace already known spells with new spells.
Etc, etc. Consult your Player’s Hand Book — now that you know the terminology and how Spell Slots work, hopefully it should make more sense.
“But…!”, I hear you cry, “my class page says stuff about preparing spells?!”
“So what is this ‘preparing’ spells nonsense?”
So, you’ve got the spells that you know, and you’ve got Spell Slots through which to cast them. What does preparation have to do with any of this?
Many classes need to prepare their spells before they actually cast them. This means choosing Spells from your available Spells and “placing the spells into your mind”, ready for casting.
Hoho! Another example!
Mary is playing Alais, a 3rd level Cleric. That means she has four 1st level Spell Slots, and two 2nd level Spell Slots.
The PHB says (and I’m paraphrasing here, plus emphasis is mine):
When you prepare your spells, choose from the Cleric list. Choose a number of spells equal to your Cleric level plus your Wisdom modifier. The spells must be of a level for which you have Spell Slots.
Well, Alais has a Wisdom of 16, putting her Wisdom modifier at +3. That means she can prepare six Cleric spells (three Cleric levels + Wisdom modifier of +3).
Each spell she chooses to prepare must be of a level that she has Spell Slots levels for — so in this case, 1st or 2nd level spells. So, after a long rest, Alais decides to prepare the following spells:
Bless (A 1st level Spell)
Detect Magic (A 1st level Spell)
Inflict Wounds (A 1st level Spell)
Hold Person (A 2nd level Spell)
Prayer of Healing (A 2nd level Spell)
Zone of Truth (A 2nd level Spell)
Now, as she’s out-and-about on her adventure, she can cast any of these prepared spells she likes, using the Spell Slots rules explained earlier.
A day of spell casting for Alais could look like any one of the following:
- she ends up needing to cast Bless a whole bunch. She casts it three times using three 1st level Spell Slots, then twice more using her two 2nd level Spell Slots (as Bless gets a nice bonus when cast with a higher level Spell Slot) then finally one more time with her last 1st level Spell Slot. She takes a long rest, and gets all her Spell Slots back.
- she casts Bless, Detect Magic, and Inflict Wounds, all with 1st level Spell Slots. She ends up not needing to cast any more magic that day. She takes a long rest, and gets all her Spell Slots back.
- she casts Prayer of Healing twice, using up both her 2nd level Spell Slots. She wants to cast Zone of Truth, but is out of 2nd level Spell Slots! So she casts Inflict Wounds instead (she hasn’t used any of her 1st level Spell Slots yet) hoping that a little pain will get the truth out of the orc.
Notice how she didn’t have to prepare the same number of spells by level to Spell Slots by level, or that she doesn’t have to prepare the same spell twice to cast it twice.
Another way of thinking of it is like:
“OK, my Class has 30 spells. I prepare 10 in my mind, ready for casting. When I want to cast one, I use up a Spell Slot (of which I have 6 of varying levels)”
Couple of things to note here:
- a spell caster doesn’t need to re-prepare her spells after every long rest — only if she wants to prepare new ones. Once prepared, they are in her mind permanently until others are prepared and take their place.
- casting a prepared spell only “uses up” a Spell Slot — it doesn’t remove the spell from your list of prepared spells (same as the point above; the prepared spells are in your mind until you prepare new ones).
Again, your class most likely has its specific rules regarding how you prepare your spells. For example;
- Wizards have to prepare and learn spells.
- Clerics prepare spells but don’t learn spells. They have access to all the Cleric spells when choosing their day’s spells to prepare.
- Sorcerers learn spells but don’t prepare spells. As long as a Sorcerer has the Spell Slots available, they can cast any spell they know, whenever.
“Wait, I’m playing as a Warlock, and it’s confusing as heck!”
Yep, you’re not wrong.
It’s out of the scope of this article to deep dive into every class, but I want to finally cover off the core difference between Warlocks and other spell casters. It seems simple, but has tripped up literally every new player I’ve ever played with. Here goes:
Instead of gaining multiple Spell Slots of different levels when they level up, a Warlock’s Spell Slots are all the same level.
For example, a 10th level Warlock has two Spell Slots. Both of these Spell Slots are 5th level. When the Warlock becomes level 11, they will have now have three Spell Slots — all three of these Spell Slots are 5th level.
Wait, what? Only 2 Spell Slots? What the hell?! I’m basically useless then!
Nope— here’s the kicker: Warlocks don’t need to prepare spells, and they get their Spell Slots back after Short Rests as well as Long Rests. This, combined with Eldritch Invocations (basically mini power ups) makes Warlocks more than able to stand toe-to-toe with other spell casters.
“Wait, wait! You missed ‘cantrips’? What the hell is a cantrip?”
O, ye’ of little faith. I didnae’ miss them — I left them to last, cus’ they’re so easy.
Cantrips can be cast without preparing them and they don’t use up any Spell Slots. Yep, that’s right — if you know a cantrip, you can cast it for free, whenever you want, however many times you want. Boom — free magic, all day, every day.
And that’s that.
Final tl;dr points;
- Every class uses Spell Slots to cast their Spells.
- A Spell must be cast in a Spell Slot that is equal to the Spell’s level or higher. Why cast a Spell in a Spell Slot higher than itself? Cus’ it usually gets a sweet buff.
- Some classes need to learn new spells, and thus know a limited selection of their classes’ spell list. They usually learn new spells when they level up or via in-game actions. Other classes “know” their entire spell list, and can use that entire list for their spell casting.
- Some classes have to prepare spells ahead of time. They prepare a number of spells in their mind, and then cast these prepared spells via (or “through”) their Spell Slots. Some classes don’t need to prepare their spells, meaning they can cast any spell they know, whenever they want, as long as they have the Spell Slots for it.
- Warlocks are the oddball — they don’t have Spell Slots of different levels. Instead, they have very few Spell Slots of the same level, and that level increases as the Warlock gains levels. Warlocks get these Spell Slots back after Short Rests.
- Cantrips are free magic — if you know a cantrip, you can cast it as many times as you want, whenever you want. Cantrips don’t need to be prepared, and they don’t use up Spell Slots.
That’s it! As I said, there are further quirks to learn (Sorcerers have Sorcery Points, Paladins don’t get cantrips, all sorts of madness) but these extra class specific rules should be easier to understand now that you get the core rules of how every spellcasting class works.
Now go forth, and do yo’ magic!
“If I ever have to type the words “Spell Slot” again I’m gonna lose my f**king mind” — me, just now.
Hopefully that clears some things up!
Found this link somehow, and you have no idea what D&D is but all of the above sounds, like, totally rad? Check out my intro to D&D piece.
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Images are, in order;
Voidwalker by Chase Stone
Usurper by Yongjae Choi
Blood Shaman by Conor Burke
Ley Weaver and Lore Weaver by Livia Prima
Images originally found from ImaginaryWizards and ImaginaryWitches
