The rules for how you can cast multiple spells in a turn have slightly changed in the new 2024 rules. In some areas they are more permissive, and in others they are less.
The main rule is:
“On a turn, you can expend only one spell slot to cast a spell.”
The other rule, relevant to Sorcerer metamagic Quickened Spell is:
“You can’t modify a spell in this way if you’ve already cast a level 1+ spell on the current turn, nor can you cast a level 1+ spell on this turn after modifying a spell in this way.”
The rules are more permissive by allowing combining with Bonus Action spells, not just cantrips, but other spells that don't use slots, such as free daily spells (e.g. Fey Touched), Aberrant Sorcerer Psionic Sorcery, and Warlock Mystic Arcanum.
Downsides are that you generally can't cast Reaction spells for your own spells, such as Silvery Barbs or Counterspell (an opposing Countspell) -- you either need to not use a slot, or use teamwork -- and that Action Surge no longer allows spellcasting.
Sorcerer metamagic Quickened Spell still restricts any other Level 1+ spell, so you need to quicken the main spell and can then use a cantrip (and not the other way around). Because of the Level 1+ restriction, it is irrelevant whether you use a slot or not.
A table of specific combinations is provided.
Allowed action combinations
The table below shows the different main Action combinations, with either Bonus Actions, Reactions, or other actions, and shows whether they are allowed or not.
The tags indicate whether an action uses a slot, is a quickened spell, is Level 1+, or is not a spell.
| Main Action | |||||
|---|---|---|---|---|---|
| Cantrip, e.g. True Strike or Eldritch Blast | Levelled spell (using slot), e.g. Fireball slot 1+ | Free spell, e.g. Shadow Touched Invisibility 1+ | Aberrant Psionic Sorcery, e.g. Dissonant Whispers 1+ | Warlock Mystic Arcanum, e.g. Scatter 6+ | |
| Bonus Action | |||||
| Bonus action cantrip, e.g. Shillelagh | yes | yes | yes | yes | yes |
| Bonus action spell (using slot), e.g. Misty Step, Healing Word slot 1+ | yes | NO (a) | yes | yes | yes |
| Free bonus action spell, e.g. Fey Touched Misty Step 1+ | yes | yes | yes | yes | yes |
| Sorcerer metamagic quickened cantrip, e.g. Eldritch Blast quick | yes | NO (b) | NO (b) | NO (b) | NO (b) |
| Aberrant sorcerer quickened Psionic Sorcery quick 1+ | yes | NO (b) | NO (b) | NO (b) | NO (b) |
| Sorcerer metamagic quickened spell, e.g. Fireball slot quick 1+ | yes | NO (a,b) | NO (b) | NO (b) | NO (b) |
| Warlock bonus action Mystic Arcanum, e.g. Blade of Disaster 6+ | yes | yes | yes | yes | yes |
| Non-spell power, e.g. Eladrin Fey Step or Monk Shadow Step n/a | yes | yes | yes | yes | yes |
| Reaction | |||||
| Reaction using a slot, e.g. Silvery Barbs or Counterspell slot 1+ | yes | NO (a) | yes | yes | yes |
| Reaction not using a slot, e.g. Fey Touched Silvery Barbs 1+ |
yes | yes | yes | yes | yes |
| Warlock reaction Mystic Arcanum, e.g. Soul Cage 6+ |
yes | yes | yes | yes | yes |
| Other | |||||
| Action Surge spell (Magic action not allowed) n/a | NO (c) | ||||
| Haste spell (Magic action not allowed) n/a | NO (c) | ||||
| Wild Magic Surge spell 1+ | yes | yes | yes | yes | yes |
Disallowed actions
Combinations not allowed are indicated in the table above:
(a) Can only expend one slot to cast a spell per turn
(b) Quickened spell metamagic does not allow you to cast another Level 1+ spell
(c) Action Surge can't be used to take the Magic action (and Haste never could)
Spells without slots
Common sources of non-slot spells include:
- Cantrips
- Free uses from Fey Touched, Shadow Touched, and similar
- Aberrant Sorcerer Psionic Sorcery
- Warlock Mystic Arcanum
However the separate rules for Quickened Spell don’t allow it to be combined with a Level 1+ spell (whether or not using a slot).
Reaction spell combinations
In general you can no longer Silvery Barbs saves against your own spells, nor Counterspell a Counterspell against one of your spells (unless one of the spells isn't using a slot). Teamwork still works, i.e. Silvery Barbs on a save for another caster's spell.
Also, the Reaction spell combinations above are for combining only with the main action spell. If you also used a quickened spell (or a bonus action spell using a slot) then those restrictions would also apply.
e.g. Bonus Action quickened Fireball using a slot, then a cantrip like Vicious Mockery, then you could not cast Silvery Barbs (whether or not using a slot) due to the quickened spell Level 1+ rules.
Wild Magic Surge from quickened spell
If a sorcered used quickened spell with a slot, and then triggered a Wild Magic Surge that cast another spell, then the Wild Magic Surge is the more specific rule and still allows that spell to be cast (overriding the quickened spell rules).
Maximum number of (levelled) spells cast
With the right combination of non-slot spells, you are still able to cast multiple levelled spells per turn, e.g.
- Bonus Action: Fey Touched Misty Step (doesn't use a slot)
- Action: Fireball, using a slot
- Reaction: Silvery Barbs, via Fey Touched (doesn't use a slot), on a creature that made their save against the Fireball
A Wild Magic Surge result, e.g. 57-60, could cause you to cast another spell, without using a slot.
The Wild Magic result 53-56 could also give you an action you could use to cast another spell, provided it doesn't use a slot, e.g. Shadow Touched Invisibility. (Because Wild Magic only triggers when you use a slot).
Wild Magic is generally only once per turn, as you can only have one slot per turn, so there is no potential infinite loop.
However in theory you could roll Wild Magic 01-04 ten times in a row, then on the elventh round roll 53-56 ten times, plus once more for the spell you cast that turn for 3+11 = 14 total spells.
Maybe there is a way to get even more?