Spellcasting rules you never knew

Part One

Part Two

Part Three

Over the last month, I have written three posts examining some of the most easily overlooked rules of the Player’s Handbook. Today I am looking at Chapter 10: Spellcasting. I am not doing Chapter 11: Spells because there are more than 300 spells in the PH alone! However, I might write future posts about specific spells that are ‘tricksy’ or difficult to run, like this post on counterspell.

As always, if I’ve made any howlers, let me know in the comments. And the usual disclaimer: this post is about rules as written (or, occasionally, rules as intended). Feel free to ignore them if it makes the game more fun!

Chapter 10: Spellcasting

There are thousands of spells beyond the ones in the PH. (201)

The PH has 361 spells. There are a further 95 in Xanathar’s Guide to Everything and another 21 in Tasha’s Cauldron of Everything. But if the DM wants to create a new spell, they are free to do so.

A cantrip is a 0-level spell. (201)

This came up in my group’s boss fight against Zargon, an elder evil who was immune to spells of 6th level or lower. ‘Does that include cantrips?’ Yes, because they are 0-level spells.

Wizards are the only class who can cast ritual spells even if they are not prepared or known. (201)

All other classes need the Ritual Caster feat for that (PH 169).

Rituals still require components and concentration if this were true for the original spell. (201)

Rituals take longer to cast and don’t consume spell slots. Otherwise, they follow the rules of spellcasting as normal.

If you cast two spells on your turn, one of them must be a cantrip. (202)

This is such an important rule that it is explicitly highlighted as one of ‘ten rules to remember’ in Xanathar’s and Tasha’s. An example: if you cast misty step as a bonus action, you are limited to cantrips for the rest of your turn. (Theoretically, you could cast three spells in a round: one as a bonus action, like misty step, one as a reaction, like counterspell, and one, a cantrip, as an action. A fighter using Action Surge could cast another cantrip in addition to this.)

There are 27 spells in the PH which you can cast as a bonus action. Here they are:

Some spells take longer than an action to cast. (202)

Lots of them, actually: 17 percent of the spells in the PH.  

Spells with verbal components must be chanted. (203)

I point this out because players sometimes want to cast a spell stealthily. I’m not sure you can ‘chant’ quietly. If you want to cast a spell quietly, I think you need to use the sorcerer’s Subtle Spell ability.

Somatic components require a free hand. (203)

But: see below.

A character can use a spell component pouch instead of a spellcasting focus. (203)

This is particularly useful if you are a multiclassed spellcaster as different classes have different spellcasting foci.

A material component (or spellcasting focus) can be held in the same hand that performs somatic components.

Handy. However:

If a spell has a somatic component, but not a material component, you need a hand free to perform the somatic element. (203)

This was clarified in Sage Advice. I’ll quote their example below:

A cleric’s holy symbol is emblazoned on her shield. She likes to wade into melee combat with a mace in one hand and a shield in the other. She uses the holy symbol as her spellcasting focus, so she needs to have the shield in hand when she casts a cleric spell that has a material component. If the spell, such as aid, also has a somatic component, she can perform that component with the shield hand and keep holding the mace in the other.

If the same cleric casts cure wounds, she needs to put the mace or the shield away, because that spell doesn’t have a material component but does have a somatic component. She’s going to need a free hand to make the spell’s gestures. If she had the War Caster feat, she could ignore this restriction.

Spell components can be expensive. (203)

Sometimes you can handwave this stuff, but sometimes it matters. For example, 1st-level spellcasters probably can’t afford the diamond required for chromatic orb or the pearl required for identify.

Some components are consumed by casting the spell. (203)

Let’s have a look at some of the more notable ones:

• revivify consumes 300 gp worth of diamonds;
• stoneskin consumes 100 gp worth of diamond dust, as does greater restoration;
• raise dead consumes a diamond worth at least 500 gp;
• heroes’ feast consumes a gem-encrusted bowl worth at least 1,000 gp;
• resurrection consumes a diamond worth 1,000 gp (what is it with diamonds?);
• simulacrum consumes a powdered ruby worth 1,500 gp (plus a load of ice and snow, among other things);
• true resurrection consumes a sprinkle of holy water and diamonds worth at least 25,000 gp.

Dying is expensive.

You can end concentration at any time. (203)

Useful to know.

If you take damage from multiple sources, you make a separate concentration save for each source of damage. (203)

The damage might be quite minimal, but if you have to make that save repeatedly, your chance of maintaining concentration start to look slim.

You lose concentration if you are incapacitated. (203)

And, by extension, paralysed or stunned.

To target something, you must have a clear path to it. (204)

Jeremy Crawford has clarified that the intent here is ‘a path clear of total cover.’ Half cover (eg, an ally in the way) is not a problem, nor is obscurement.

The same applies to the point of origin for spells with an area of effect. (204)

To quote verbatim:

If you place an area of effect at a point that you can’t see and an obstruction, such as a wall, is between you and that point, the point of origin comes into being on the near side of that obstruction.

So, no, you can’t let off a fireball round the corner of a corridor.

A spell does not need line or sight unless it says so. (204)

This links to the point above about a clear path to the target. Jeremy Crawford has clarified this in an official D&D podcast. Thus, a closed window blocks casting, even if you can see the target behind it, but a narrow arrow slit does not.

Some spells can only deal damage to creatures, not objects.

This was clarified in Sage Advice. You can’t use eldritch blast to smash down a door, for example. Essentially, the target specifications are intentional. 

If a spell targets ‘a creature’, you can target yourself. (204)

Unless, of course, the spell specifically states otherwise (eg, ‘a hostile creature’, ‘a creature other than you’).

Rules as written, it is not evil to create undead. (204)

However: the rules are clear that it is ‘not a good act’, and ‘only evil casters use such spells frequently.’

Total cover can block an area of effect spell. (204)

Or, as the PH puts it:

A spell’s effect expands in straight lines from the point of origin. If no unblocked straight line extends from the point of origin to a location within the area of effect, that location isn’t included in the spell’s area. To block one of these imaginary lines, an obstruction must provide total cover, as explained in chapter 9.

The effects of the same spell cast multiple times don’t combine. (205)

This is another one of the rules called out in the introductions to Xanathar’s and Tasha’s.

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