I recently started reading through the Shannara books by Terry Brooks, and it got me thinking about how the notion of the wishsong would translate into a system like D&D.

My (very) rough idea right now is a sub-class of sorcerer who can learn spells from any school or class as long as that spell uses only verbal components.

I found a pretty good tool on a site that let me filter to get a list of all verbal-only spells. Level-wise, the list looks reasonably well-distributed and has a decent mix of combat and non-combat spells. That said, I don't have an encyclopedic knowledge of D&D spells and my experiences with the Sorcerer class is limited.

Would these spells be seriously unbalanced when combined with the class features of a sorcerer?

To be clear, taken as a whole, this list will probably still be too limited and will require adding in some additional spells to round it out later. My primary concern is identifying any game-breaking outliers before I start making further changes.

Cantrips: Lightning Lure, Sword Burst, Thaumaturgy, Vicious Mockery
Lvl 1: Cause Fear, Command, Compelled Duel, Dissonant Whispers, Ensnaring Strike, Faerie Fire, Hail of Thorns, Healing Word, Hunter's Mark, Searing Smite, Thunderous Smite, Wrathful Smite, Zephyr Strike
Lvl 2: Blindness/Deafness, Blur, Branding Smite, Earthbind, Knock, Misty Step,
Prayer of Healing, Warding Wind
Lvl 3 Aura of Vitality, Blinding Smite, Crusader's Mantle, Mass Healing Word, Thunder Step
Lvl 4: Aura of Life, Aura of Purity, Dimension Door, Guardian of Faith, Guardian of Nature, Staggering Smite
Lvl 5: Banishing Smite, Circle of Power, Contact Other Plane, Destructive Wave, Far Step, Geas, Immolation
Lvl 6: Otto's Irresistible Dance, Scatter, Word of Recall
Lvl 7: Divine Word, Power Word Pain, Teleport,
Lvl 8: Glibness, Power Word Stun
Lvl 9: Power Word Kill, Time Stop, Wish

This is a significant weakness for the subclass

This list of spells is extremely limited. If you subtract out the sorcerer spells from the new list and compare it to the default sorcerer list, you are trading...

• 26 cantrips for 2 new ones


• 25 1st-level spells for 13 new ones


• 28 2nd-level spells for 2 new ones


• 25 3rd-level spells for 4 new ones


• 13 4th-level spells for 5 new ones


• 16 5th-level spells for 5 new ones


• 15 6th-level spells for 2 new ones


• 9 7th-level spells for 1 new one


• 5 8th-level spells for 1 new one


• 6 9th level spells for 0 new ones

Your spell selection will be extremely limited as a result of this feature. There would have to be sizable compensation in the rest of the subclass features to account for this drastic reduction in versatility.

Another problem is that over the course of a sorcerer's adventuring life, they gain 6 cantrips while your subclass only has access to 4. I'm not sure how you would resolve this, but the subclass should probably account for this disparity.

Paladin spells

One possible redeeming factor is the availability of a handful of high-level paladin spells such as staggering smite and banishing smite. These spells are usually only available to paladins of level 13 (for the 4th level ones) and level 17 (for the 5th level ones), but would come online much sooner for your subclass. Usually the only way to get access to these spells earlier is through the bard's Magical Secrets feature.

Bards will get access to at most six of these over the course of their adventuring career (but reasonably only two as the other four could be used for much more powerful options at higher levels), while your sorcerer subclass gets access to all of them. Overall though, I doubt this makes up for the loss of so many spell options.

One issue you're likely to run into with this design, is that the list of spells with only verbal components is extremely limited. For example, there are two cantrips in the Player's Handbook with only verbal components, Xanathar's Guide to Everything has none, and the Sword Coast Adventurer's Guide has two more.

This would be problematic for a sorcerer, in that they will never be able to have more cantrips than they start with at level 1 (4 cantrips).

Outside of cantrips, the total list of spells is still very small and it only gets worse at higher level (there are a total of 11 spells level 6-9 that only have verbal components).

As noted below, this is basically a weaker version of a Divine Soul Sorcerer, but with access to several Ranger and Paladin exclusive spells. Those classes are half casters, so your sorcerer gets access to spells that would usually only be available to higher level spells. That said, none of them are particularly powerful (Swiftquiver, for example, isn't present).

Overall, I'd say this class is a less powerful version of arguably the best Sorcerer subclass. The sorcerer is generally acknowledged to be underpowered, so I'd guess this would be relatively underpowered.

It is still weak even if you add these above the usual Sorcerer list

Divine Soul Sorcerers can learn spells from the Sorcerer and Cleric list.

They also get 2d4 per short rest to an attack or save, and empowered healing and wings and half their hit points for a bonus action.

I am comparing to the arguably best Sorcerer origin, but as long as it is weaker than the current best, it cannot be overpowered.

My recommendation is to use Divine Soul as a template, so add these spells, and some other features for levels 1, 6, 14 and 18.

The spells are deeply restricted, but it doesn't have to be this stark.

The size of the cantrip list alone is an issue. The fact that many of these effects are not amazing for the sorcerer is another. Many of them, for example, strognly encourage melee combat - not an area that the sorceror particularly shines in. By contrast, you're missing almost all of the blasting spells that are the default sorceror's bread and butter.

On the other hand, you do have class features to play with. One of the more obvious solutions for this one would be to have a class feature that lets you skip the material components (within a certain budget) and the somatic components, but removes access to the Subtle Spell metamagic or any other form of removing access to verbal components.

Of course, you might still want to do some surgery to the spell list after this. In particular, the powers described for the various incarnations of the elfsong aren't necessarily well-aligned with either the Sorceror list or the Verbal-only list. It's going to have to be up to you to decide how far to take that, though.

Nothing Gamebreaking, but a Problematic Subclass

The good news is there really doesn't seem to be any spells that are overpowered (well, Wish, but Sorcerers get that anyway), so the answer your primary stated question/concern is a simple "no, none of these spells will break your game". Lets move on to the trouble:

Weak, Though This May Not Bother You Thematically

As others have discussed at length, this subclass is getting a very limited selection of spells versus other full spell-casters. Perhaps a larger issue, however, is that they simply don't have a viable list of spells at certain levels. I think a sorcerer without stronger attack cantrips is probably going to be a pretty useless party member for the first couple levels (when they have few spell slots) compared to any other subclass of any class. Meanwhile in the top two tiers they get very few spells at all, which means that spell-wise they will start to become a comparatively even weaker subclass after level ten.

However this is a subclass built strongly around a theme, and thematic strength can offset mechanical weakness to people who care enough about theme. Still having mechanics that bear out the promise of the theme is important even to many people who prefer role-play to roll-play.

Stronger for a Fighter-Caster Subclass or with Some Special Ability to Use Related Spells. But This May Bother You Thematically

The spells they gain are disproportionately Paladin and Ranger spells, and many require a melee attack. This would suggest that if their subclass features involved weapons, armor, an extra attack at level six (like valor bards, sword bards and bladesingers), something to give them semi-competitive hit points, and/or other features to make them useful in non-magical combat then this might be a competitive subclass.

If that is completely off theme (I which suspect it is for a "wishsong" theme) then perhaps they need some other special ability to make a more sorcerer appropriate at-will attack with which various smites and such can be used effectively. It just seems like without some sort of extra ability to take full advantage of smites, hunters mark, etc they are trading way too much for things they can't even get much use from and which probably don't bear out the theme.

What do You Want Theme-wise?

It seems like the real question is not whether these added spells are gamebreaking. Unless there is a particular exploit with metamagic it is hard to see how any RAW spells could be given to a Sorcerer and really "break" the game and most the usual suspects are spells that Sorcerers, or at least Divine Soul Sorcerers, already get. It seems like the real question, and the thing you will have to evaluate the specific spells being given for, is whether they suit the theme you are trying to achieve.