The old rule was you could only cast one leveled spell per turn.  This meant that any magic item that used the words "cast" counted as a spell and most of them did.  A wand of Fireballs specified "cast" so you could not cast it and also cast a lightning bolt.

A few of the wands however did not use the word Cast, Wand of Fear for example.  Technically a sorcerer could use a Wand of Fear, and also Quicken a Lightning Bolt spell.  Same with a Potion of Flying. 

Now, the rules have changed. The new 2024 rules state:

(page 236 of Players Handbook)

On a turn, you can expend only one spell slot to cast a spell. This rule means you can't, for example, cast a spell with a spell slot using the Magic Action and another one using a Bonus Action on the same turn.

Technically  ALL wands, scrolls, potions etc. can be cast without using a spell slot.  So does a Sorcerer now gain the ability to use a Wand of Fireballs and Quicken a leveled spell?

The old rule was more complex than "one leveled spell per turn" with some tricky exceptions and exploits, which is what the new rule is trying to address. Regarding Quicken, the new effect for Quicken says "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," so it does not combo with any method of casting a leveled spell without using a spell slot.

This is the typical wordings in 2014, for example in Wand of Fireballs and Wand of Magic Missiles: "you can use an action to expend 1 or more of its charges to cast the [...] spell from it"

It's also important this sentence about Spells in the 2014 DMG, p. 141: "Some magic items allow the user to cast a spell from the item, often by expending charges from it."

One thing I'd like to compare in the 2024 DMG is whether the usual wording for magic items that allow the user to cast a spell from them has changed. If it hasn't, and the magic item still performs the effect of the spell while the spellcaster is considered the one casting it, I don't clearly see why Quickened Spell wouldn't work with magic items.

EDIT: added a further explanation here.

I don't see how if the spellcaster is considered casting it the clause in Quickened Spell wouldn't come into play to disallow a second leveled spell that turn.

Quote from Mog_Dracov >>

The old rule was you could only cast one leveled spell per turn.

 There was no such old rule, there was a rule about casting a spell on a bonus action:

Bonus Action

A spell cast with a bonus action is especially swift. You must use a bonus action on your turn to cast the spell, provided that you haven't already taken a bonus action this turn. You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action.

This did not prevent you from say, casting two spells in the same turn using Action Surge in 2014 but in 2024 you can no longer do that.

In regards to sorcerer, yes you can use Quickened Spell on any spell, there is no limitation here, so if it's cast from a scroll or an item, it should work as long as it counts as casting a spell but as per the caveat already mentioned by The_Ace_of_Rogues, you would then be unable to cast another levelled spell on the same turn, you'd be restricted to cantrips.

Now, it is notable that Potions would generally be the exception here, in that the ones that reference spells typically say "you gain the effect of X spell" rather than "you cast X spell with this item".

Quote from The_Ace_of_Rogues >>

The old rule was more complex than "one leveled spell per turn" with some tricky exceptions and exploits, which is what the new rule is trying to address. Regarding Quicken, the new effect for Quicken says "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," so it does not combo with any method of casting a leveled spell without using a spell slot.

I don't understand how people are voting Yes in this poll

Quickened Spell

Cost: 2 Sorcery Points

When you cast a spell that has a casting time of an action, you can spend 2 Sorcery Points to change the casting time to a Bonus Action for this casting. 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.

Spell slots are irrelevant. If you cast a leveled spell by any means, you can't also Quicken a leveled spell

One edge case of an adventure-specific item not meshing with the new rules doesn’t discredit the idea of backwards compatibility, it just means the DM will need to do more of what they’ve already been doing and make a call if and when this actually crops up.

Quote from FutureSightRunner >>

Then they are going to have to go back into LMOPSO and Ettera the Mind Crystal(Quickened) as it is an object/magic Item that allows the user to Quicken a spell.

There's nothing in the mind crystal that needs changing based on the 2024 rules

It lets you Quicken a spell. Great. That still doesn't let you cast a second leveled spell on your turn

Quote from The_Ace_of_Rogues >>

I don't see how if the spellcaster is considered casting it the clause in Quickened Spell wouldn't come into play to disallow a second leveled spell that turn.

 I totally agree with you.

My first answer was about how Quickened Spell interacts with Magic Items. From what I understand (and I think it's the agreement in the thread), you can only quicken 1+ spells once, not twice, regardless of whether you're using a Magic Item, Spell Scrolls, your own spell slots, or traits/features/feats that allow you to cast prepared spells without using spell slots.

Sorry if I wasn't clear :(

Quote from FutureSightRunner >>

For now, the vote can reflect a yes vote, as ether set of rules allows for a situation where two Quickened Spells could be cast in a single round, just not on a single turn.

This is simply incorrect. There is no circumstance in which you could use Quicken twice in a round, because there is no circumstance in which you can get two Bonus Actions in the same round. You get one Bonus Action, and it can only be taken on your turn

Bonus Actions

Various class features, spells, and other abilities let you take an additional action on your turn called a Bonus Action. The Cunning Action feature, for example, allows a Rogue to take a Bonus Action. You can take a Bonus Action only when a special ability, a spell, or another feature of the game states that you can do something as a Bonus Action. You otherwise don’t have a Bonus Action to take.

You can take only one Bonus Action on your turn, so you must choose which Bonus Action to use if you have more than one available.

You choose when to take a Bonus Action during your turn unless the Bonus Action’s timing is specified. Anything that deprives you of your ability to take actions also prevents you from taking a Bonus Action.

While I don't have access to the rules for this "mind crystal" magic item, I am confident in saying that it's a mistake to assume that it follows the same rules that the Sorcerer uses when he attempts to Quicken a spell by using his Metamagic class Feature.

Just like when a magic item is capable of casting a spell, you are never actually using a particular class's Spellcasting class Feature to do so, you are using the rules for magic items and the particular rules that are specified in the particular magic item's description . . . the same concept applies here.

What people typically refer to as "the rules for casting a Quickened spell" is actually a rule that is found within a class Feature for the Sorcerer class.  That class Feature is called "Metamagic", acquired by Sorcerers at Level 2, which provides a list of several metamagic options, how to gain access to them, and how to use them when using that class Feature.  There is no "general rule" for a Quickened spell per se.  It's defined within a class Feature.

If a magic item is created that provides a similar feature, you are not actually using the Sorcerer's Metamagic class Feature when using this magic item -- you are using whatever rules are written into that magic item's description.  If those rules are somehow different, then that magic item is irrelevant to this discussion, which is about the Quickened Spell option that is provided by the Sorcerer's Metamagic class Feature.

Quote from AntonSirius>>

Quote from FutureSightRunner>>

For now, the vote can reflect a yes vote, as ether set of rules allows for a situation where two Quickened Spells could be cast in a single round, just not on a single turn.

This is simply incorrect. There is no circumstance in which you could use Quicken twice in a round, because there is no circumstance in which you can get two Bonus Actions in the same round. You get one Bonus Action, and it can only be taken on your turn.

 The only case I know is with the Thief's Reflexes feature. At Level 17. No more. No less 😅

Quote from tarodnet >>

Quote from AntonSirius>>

Quote from FutureSightRunner>>

For now, the vote can reflect a yes vote, as ether set of rules allows for a situation where two Quickened Spells could be cast in a single round, just not on a single turn.

This is simply incorrect. There is no circumstance in which you could use Quicken twice in a round, because there is no circumstance in which you can get two Bonus Actions in the same round. You get one Bonus Action, and it can only be taken on your turn.

 The only case I know is with the Thief's Reflexes feature. At Level 17. No more. No less 😅

I stand corrected. There is one circumstance

“Turn” is very clearly defined- the order is determined by initiative, and during each turn a creature can move and take actions and/or bonus actions. Barring the Ready Action or an effect that specifically allows it as a Reaction, there’s no way to use an item on another creature’s turn.

Command applies on the target's next turn, so there's no possible way it can produce an out of turn action, even assuming your DM let you try and get something like that out of it.

Barring a feature that allows another creature to use its Reaction to do something, there is no way to command a creature and cause it to take an action outside of its turn in combat, and I’m not familiar with any that would allow for the casting of a spell via feature, spell slot, or magic item. If you’re acting outside of combat/initiative then obviously you can’t apply turn rules, but to refer back to your earlier post I’m not sure how a round could be in play when turns aren’t. I doubt the DMG is going to say much about adjudicating timing outside of combat; that’s a fairly common sense/whatever feels right area. But, by definition, if turns and rounds are not being tracked then two instances of the same event cannot happen in the same turn, so that doesn’t really have any bearing on the original question.

While beyond the topic of this conversation, I wonder how the 2024 Thief's Fast Hands, which now allows you to make a Magic action as a bonus action to activate a magic item requiring that action, would interact with an item like a wand of fireballs or lightning.

(For the sake of argument, let's say they are multiclassed to meet the attunement requirements)

Would the Thief be able to, as a bonus action, cast the magic item's spell, since they are still performing a magic action?

Quote from Galvanic_Gray >>

While beyond the topic of this conversation, I wonder how the 2024 Thief's Fast Hands, which now allows you to make a Magic action as a bonus action to activate a magic item requiring that action, would interact with an item like a wand of fireballs or lightning.

(For the sake of argument, let's say they are multiclassed to meet the attunement requirements)

Would the Thief be able to, as a bonus action, cast the magic item's spell, since they are still performing a magic action?

 Assuming that the Wand of Fireballs will now require the Magic action to be activated (we'll see in the new DMG), a Thief could use Fast Hands to use the Wand using a Bonus Action, yes.

Level 3: Fast Hands

As a Bonus Action, you can do one of the following.

Sleight of Hand. Make a Dexterity (Sleight of Hand) check to pick a lock or disarm a trap with Thieves’ Tools or to pick a pocket.

Use an Object. Take the Utilize action, or take the Magic action to use a magic item that requires that action.

There is a related post about Spell Scrolls and Magic action here: Who can use Spell Scrolls - Rules & Game Mechanics

if I am not a magic user, can I use the sylvan talon scimitar to cast message using a magic action?