Sorcery points are not restricted in which spells they can affect.
Other class features similarly work between classes, as the classes merely grant abilities and few of them state that they have any form of exclusivity. Metamagic abilities and other methods of spending Sorcery Points are not restricted to only affecting Sorcerer spells.
Considering that in ...
Twinned Spell doesn’t actually make you “cast two spells”, it just says that:
When you cast a spell ... you can ... target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip) (PHB 102)
Note that the text says that it is the same spell. You can't concentrate on two spells as you say, the first spell's concentration ...
You can use only one Metamagic option on a spell when you cast it, unless otherwise noted.
The phrasing may seem unclear but you cannot use several metamagic options and neither can you use the same metamagic option several times on the same spell.
Here lead rules designer Jeremy Crtawford his intent for the rule on twitter:
The intent is that a sorcerer ...
Put him in armor he's not proficient in.
In 5e you cannot cast spells while wearing armor you're not proficient in. So unless the sorcerer has dipped Fighter and is therefore proficient in all armor (one of the quirks of 5e), wearing armor he's not proficient in renders him unable to cast spells. Plus, the armor makes it more difficult for him to escape ...
You might not even need Subtle Metamagic
The Knock spell states that:
[...] When you cast the spell, a loud knock, audible from as far away as 300 feet, emanates from the target object [...]
As long as you are outside the Silence when you cast the spell, but the object itself is inside, the Silence spell will absorb the loud noise.
Knock has a 60ft ...
Metamagic Adept does not give the Flexible Casting feature.
Flexible Casting is uniquely a 2nd level feature of the sorcerer class that allows a sorcerer to convert sorcery points into spell slots. This feature is not a feature of the Metamagic Adept feat, so a warlock with the feat (or anyone without at least 2 levels of sorcerer) cannot convert sorcery ...
Rule 0: You can. But you can't - and you probably shouldn't.
Combat starts when the intent to attack starts (attack or do something else harmful). You should roll initiative, and, if the player character rolls higher than the sorcerer, they have the opportunity to do something. This is the whole point of the Alert feat and the initiative system: it doesn't ...
How many Sorcery Points should this cost? Lots. At least 5, since this metamagic is better than Careful Spell, Empowered Spell and Heightened Spell combined. I'm sure you can see where I'm going with this - it's too powerful to put a realistic cost on it.
Your new metamagic option does 3 things. The first is pretty simple - it multiples damage by 1.25, or 1....
No, you can't counterspell spells with no components
Subtle spell is meant to protect against counterspelling. See this unofficial ruling from Jeremy Crawford:
Subtle Spell is meant to protect a spell w/o material components from counterspell, since you can't see the casting.
No, metamagic only takes effect when you cast the spell
All the sorcerer's metamagic abilities have wording like:
When you cast a spell that...
If you failed to cast the spell, you don't get to invoke the metamagic ability in the first place, so spending sorcery points is contingent on successfully casting the spell in the first place.
The rule on spellcasting does not say that you need a component, but:
Each spell's description indicates whether it requires verbal(V), somatic(S), or material(M) components. (PHB 203)
So technically there could be a spell that does not list any components. Subtle spell overwrites even the above rule, which it can do as a class ability is more specific ...
The spell uses the slot level, spell save DC, spell attack bonus, and spellcasting ability of the original caster, but is otherwise treated as if you cast the spell.
This says nothing about metamagic, so that aspect of the spell casting should be "treated as if you cast the spell." In effect, the ring doesn't store anything other than the spell's name, slot,...
Scrap It Completely
This ability is ridiculously complex - it involves four die rolls of five dice, multiplication, and division... and all of this before the DM even rolls any saving throws. This is going to be a nightmare to adjudicate at the table, and no DM I've ever encountered will have decided on enough positioning detail at the kinds of range you'd ...
Using Twinned Spell only uses one spell slot. This is because you are not casting two spells, rather you are making a single spell hit more than one target.
"...target a second creature in range with the same spell..."
However, it's worth noting that you can't cast Fireball with Twinned Spell.
Quote from PHB page 102 (emphasis mine)
Twinned Spell: ...
It'll work, just not the way you described.
Why your plan won't work
In your plan, you are trying to cast two bonus action spells. One is a standard cast of a Bonus Action (Healing Word) and the other is a spell converted from Action to Bonus Action via Quicken (Eldritch Blast.)
Unfortunately, you only get one bonus action per turn.
You can take only one ...
It depends on how you define "targets only one creature"
When you cast a spell that targets only one creature and doesn't have a range of self [...] To be eligible, a spell must be incapable of targeting more than one creature at the spell’s current level.
To answer this, we need to drill down and answer thoroughly what a "target" is in ...
Quickened Spell only affects the initial casting of the spell; it has no effect on actions granted by the spell
The Quickened Spell Metamagic, as you quoted, does exactly what it says: it changes the casting time of the spell from an Action to a Bonus Action. It does not do anything else.
The effect of Witch Bolt, which includes the ability to continue to ...
If the spell is on your class’s spell list, you can read the scroll and cast its spell without providing any material Components. Casting the spell by reading the scroll requires the spell’s normal Casting Time. If the spell is on your class’s spell list but of a higher level than you can normally cast, you must make an ability check ...
Dispel magic ends the effect on only one target
1. This is a confusing area. RAW would appear to suggest that dispel magic should end the effect on both targets:
The rules for twinned spells state:
When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to ...
Only when the caster is below 5th level
The errata for the PHB has clarified the restriction further from the original printing:
To be eligible for Twinned Spell, a spell must be incapable of targeting more than one creature at the spell’s current level.
By default, eldritch blast does not have a range of self and is capable of targeting only one creature. ...
No, you can't. In general, you can only use one metamagic, once, on any spell.
The only such note is this one, on Empowered Spell:
There's a simpler way to do this.
What you need is a template in a hexagonal pattern surrounding a central hex. Adapt the scale/size of the hexes to suit the spell, and all you need is two die rolls: 1d20 and 1d6.
The mechanics of your meta magic...
... would look something like this:
Spend the meta magic points.
Succeed or fail on a DC check to hit the ...
Yes, they will still take half damage.
This doesn't contradict the text at all, because you have successfully protected them from the full force of the spell. You aren't able to protect them completely, but they haven't taken the full damage the spell would have otherwise inflicted.
Two eldritch blasts is fine.
Step 1: Cast eldritch blast using Quickened Spell to make its casting time a bonus action. You can do this.
Step 2: Flip to PHB p. 203's "Casting Time" section and review the "Bonus Action" subsection:
You can't cast another spell during the same turn, except for a cantrip with a casting time of 1 action.
By the Rules as Written: Yes, you can.
First: You can cast two spells, one being a cantrip (PHB, p. 202). Since both are cantrips, your example works.
You can't cast another spell during the same turn, except for a
cantrip with a casting time of 1 action.
Secondly: You can only add one Metamagic option to a spell (PHB, p. 102). Since the wording indicates ...
RAW both effects apply, but it's not clear if the range should be 480 or 360. It depends on if you interpret double as "x2" or "+100%". While previous editions of the game made it clear that "doubling a double is a triple," as far as I can tell 5e doesn't tell you what to do either way.
However, this exact question was asked to Jeremy Crawford on Twitter, ...
No, you can not.
The rules for Metamagic contain this line
You can use only one Metamagic option on a spell when you cast it, unless otherwise noted.
Neither the Quickened Spell nor the Twinned Spell metamagic have exceptions allowing them to be used with other metamagics, so in the absence of other features allowing you to use multiple metamagics on ...
The text of Extended Spell, emphasis mine:
When you Cast a Spell that has a Duration of 1 minute or longer, you can spend 1 sorcery point to double its Duration, to a maximum Duration of 24 hours.
The text of Time Stop, emphasis mine:
9th level transmutation
Casting Time: 1 action
The newly released errata for the PHB answers this question definitively:
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.
So you can't use any form of metamagic on spells cast by your Wild ...