In response to this question, I started to think about what it means when a Wild Magic Surge results in a "You cast spell-X".

So, "specific beats general" gives:

  • You can cast a second spell when you would not normally be allowed to
  • You can cast a spell you don't know
  • If the surge forces you to cast a concentration spell you would lose any concentration spell that you currently had active
  • Subject to what the specific entry says you can target it how you like
  • Unless the specific entry prohibits it you could use metamagic on the spell

I am pretty confident in all of the above but if anyone disagrees please address in an answer.

Here comes the question.

How does this impact on your available spell slots?

"You cast ..." to me suggests that if you have an applicable slot available then you have to use it to cast the spell because that is the general rule for casting spells but if you don't then "specific beats general" and it is cast anyway.

Specific examples:

You cast fireball as a 3rd-level spell centered on yourself

This must be a 3rd level spell:

  • if you have a 3rd level slot available you have to use it?
  • if you don't, if you have 5 sorcery points and a bonus action available must you use these to get that slot?
  • if you don't have any of that then the spell goes off anyway?

You cast confusion centered on yourself.

No level specified and confusion is a 4th level spell:

  • if you have a 4th level slot available you have to use it?
  • if you have a 4th, a 6th and an 8th level slot you can choose which one to use?
  • if you have only a 5th level slot but also 6 sorcery points and a bonus action, you could choose to use the 5th level slot or use the points to create a 4th level slot?
  • if you don't have any 4th level or higher slots but you have 6 sorcery points and a bonus action available must you use these to get that slot?
  • if you don't have any of that then the spell goes off anyway?

And so on ...

  • 2
    \$\begingroup\$ Per the PHB errata spells cast via a surge do not require concentration, and can not have metamagic applied to them. \$\endgroup\$
    – Jon
    Commented May 5, 2017 at 16:43

3 Answers 3


According to WOTC developer Rodney Thompson, Wild Magic Surge wasn't intended to cost spell slots, so this should certainly be enough to prove the intention behind Wild Magic Surge.

Given the ambiguity of the RAW in this area, and the (let's face it, fairly nonsensical) consequences of deciding that Wild Magic Surge costs spell slots, I would personally stick with RAI and the considerably simpler and easier interpretation of the rules.

Besides all that, the Wild Mage is already a very underpowered option with numerous issues. Nerfing it further just seems downright cruel.


Casting Spells as part of a Wild Surge does not use a spell slot

I have to admit this answer is light on "proof" but I don't believe the Wild Surge is intended to require the sorcerer to burn a spell slot, and in any game I run I would not have it do so.

Reason #1: it's a "surge"

The Wild Surge class feature states:

your spellcasting can unleash surges of untamed magic.

Most of the items in the table are magical effects that do not say "you cast" and just cause something magical to happen without the expenditure of any resources. That provides precedent for the idea that the wild magic surge is "extra" magic beyond what the sorcerer can normally create. Thus I argue that we should interpret "you cast" in this context in the same way it would be interpreted if the caster were casting from a magic item -- as a casting that requires none of the caster's resources. They are the caster for the purposes of determining spell DC and attack rolls and maintaining concentration, if relevant, but they are not casting it from their daily spell slots, and don't require any components. (That's another issue that would come up if the spells were supposed to be cast as normal -- the sorcerer would most likely not have the components required.)

[Note: the errata for the PHB clarify that the caster does not have to maintain concentration on the wild spell: If a Wild Magic effect is a spell, it’s too wild to be affected by Metamagic. If it normally requires concentration, it doesn’t require concentration in this case; the spell lasts for its full duration.]

Reason #2: The rules for casting from a wild surge should be consistent

We have no precedent in the rules that I know of where things take up resources if they happen to be available, but happen anyhow if the resource don't happen to be available. Thus to say, your wild surge uses up an appropriate spell slot and material components if you happen to have them available, but the spell happens anyhow even if you don't, would be odd in a way that is (I think) unprecedented.

Reason #3: There are exceptions to the use of spell slots

The PHB p. 201 states:

When a character casts a spell, he or she expends a slot of that spell's level or higher....

However further down it also states:

Some characters and monsters have special abilities that let them cast spells without using spell slots.

Although the Sorcerer's wild magic surge is not listed as an example there, the three examples given are clearly not intended to be an exhaustive list. It is reasonable to assume that the Sorcerer's involuntary casting may also fall under this exemption.

Reason #4: it doesn't makes sense that the developers would have left so many obvious questions unanswered if they wanted it to work that way

For the reasons you mention above (the caster might not have slots of the appropriate level available, either that day or at all yet) it doesn't make sense for this feature to require the use of a spell slot. It especially doesn't make sense for it to only sometimes require a spell slot. If the developers had wanted it to burn a spell slot, they would surely have realized that there would be times when a slot would not be available, and would have addressed these cases in the rules.

I realize that the latter especially is a weak argument, since there is much left unstated in 5e, but this is a rather huge set of obvious contingencies that has been left totally unmentioned.

  • \$\begingroup\$ I like your reasoning but can you address "When a character casts a spell, he or she expends a slot of that spell’s level or higher, effectively “filling” a slot with the spell." p.201 PH and the fact that "You cast ..." is used specifically as opposed to "This happens". Designer's not covering all the bases is par for the course in 5e (mixed sporting metaphor!) \$\endgroup\$
    – Dale M
    Commented May 4, 2015 at 3:52
  • 1
    \$\begingroup\$ However, I just edited to add that casting from an item doesn't require components -- if we imagine that the sorcerer is to cast "as usual" there would be a parallel question to this one about where the material components come from, does the sorcerer have to drop what he's holding to have a hand free (if they were casting the original spell without somatic components perhaps), etc. So I see that as one more reason to assume we're supposed to use the "from an item" type of spell casting rather than the "from my slots" type of spell casting. \$\endgroup\$ Commented May 4, 2015 at 4:12
  • \$\begingroup\$ @DaleM I added a new "reason #3" which might address "when a character casts a spell..." \$\endgroup\$ Commented May 4, 2015 at 4:29
  • \$\begingroup\$ So if you're casting a concentration based spell, and get a concentration based surge effect, you lose your desired spell & just get the surge effect? \$\endgroup\$
    – Adeptus
    Commented May 4, 2015 at 6:22
  • 2
    \$\begingroup\$ @Adaptus errata have clarified that no concentration is required on the wild surge spell. \$\endgroup\$ Commented Aug 2, 2015 at 7:58

Starting from the general rule (Player's Handbook p.201):

When a character casts a spell, he or she expends a slot of that spell’s level or higher, effectively “filling” a slot with the spell.

And the phrasing of the specific rule (Player's Handbook p.104)

You cast ...

First, there is nothing that I can see that forces you to use sorcery points to create a slot you do not have so, but you can if you want and are able to.

If you have "a slot of that spell’s level or higher" then:

  1. If the surge isn't specific about the level of the spell then you can choose what level slot to use and the spell takes effect at that level.
  2. If the surge is specific ("You cast magic missile as a 5th-level spell") then you must use a slot of that level. If you do not have a slot of that level then you must use a higher level slot but the spell does not get any additional benefits. If you got the magic missile effect above and only had a 7th level slot, you would use that but only get the 5th level effect (7 missiles), this is a case when you might choose to use your sorcery points to save that slot.

If you don't have "a slot of that spell’s level or higher" then:

  1. You cast it anyway without using a slot.

I have no opinion on the obvious corollary question - what if you don't have the V, S or M components needed for the spell?

  • 1
    \$\begingroup\$ Whatever the answer for spell slots is, it should probably be the same for components of all types. \$\endgroup\$ Commented May 4, 2015 at 4:37

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