Is an item that increases spell save DC balanced?

Question

One of my players' characters likes to use illusion spells in combat. To improve their effectiveness, he is asking me for an item that increases his spell save DC. The Rod of the Pact Keeper provides a spell save DC boost. However, it is locked to Warlocks. I'm considering giving him a similar item without the class restriction.

Example:

Ring of channeling (very rare)
While you wear this ring, the spell save DC of your spells is modified by +2.

Would it be unbalanced to have an item provide just a bump to Spell save DC?

If it is relevant, he is a level 15 Sorcerer and already has Charisma 20.

Answer 1

Probably Not

Increased Spell DC is, as you've said, very hard to find. The lack is probably due to the bounded accuracy of 5e, but the fact that it's so rare to find something to boost it is an indicator that doing so homebrew may be dangerous.

Increasing DC is generally accounted for by the increasing proficiency as you Level. While some items can force Disadvantage on a save (like a Bardic Instrument for Charm Spells), that is balanced by having a lot of enemies immune to charm or resistant to magical effects (advantage on their saves.)

An illusionist is a tricky situation. Many of their spells are either Intelligence saves (so magical resistance still works, but against INT, which is generally a lower stat for many creatures) or Investigation(INT) checks (which very few have any proficiency in.)

ASIs and Assumptions

I am assuming that this level 15 character has maxed out their Spellcasting modifier to 20/+5(charisma for the Sorcerer.) If maxed out, the only Magic Items that increase his Spell Save DC are the Tome of Leadership and Influence (Very Rare) which increases their Charisma and Charisma Max by +2 and the Robe of Archmagi(Legendary, only for Walrocks, Sorcerers, and Wizards) which increases Spell Save DC by 2.

In addition, allowing a straight +2 to DC without increasing the Spellcasting Ability could create an odd situation where your Ability Modifier for DC is different, and greater than(!), the maximum modifier for ability scores. An example of this would be either a max 20 Ability score generating a +5 modifier, except for DCs which would turn it to +7. Or a situation where someone has a Headband of Intellect which increases their Int to 19. That should generate a +4 Ability score modifier, but instead it would end up being +6, which is the equivalent of 22 Intelligence.

Other Ideas

My table uses the Variant rule in the DMG for Proficiency Dice (DMG, 263). It makes that DC swingy (could be lower than normal, could be higher), but it adds a neat effect to the DC set. And you get to roll (more) dice.

You could also look at creating a homebrew feat. Maybe give him a couple more illusion spells and allow a 1/SR ability to force disadvantage on the first save/check against an illusion? I had a feat like that for one of my characters that focused on illusions and it did make them a bit more interesting. However, illusions are very table dependent and the power of this will vary. For us, we allow illusions to impart conditions, so this gave my illusions a big boost without a huge downside. We still try to play the monsters reasonably and also balance "we're not removing this monster from the entire battle with a low level illusion spell" with "let's make this more fun"

Answer 2

This is not only balanced, but official

What you proposed is a bit under the power level of a current Rare item.

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As of the release of Tasha's Cauldron of Everything, WotC have now published items of exactly this sort for the artificer, cleric/paladin, wizard, sorcerer, druid/ranger, and bard.

Like the Rod of the Pact Keeper, each comes in Uncommon/Rare/Very Rare forms, giving +1/+2/+3 to spell attacks and save DC at the respective versions. Each also has an extra utility feature similar to the Rod's spell slot restoration, typically once per day.

Thus, with the publishing of Tasha's, a spell save-increasing magic item for other classes is now 100% a 'balanced' thing, when compared to official published magic items. As written in the question, it's probably a bit too much for an Uncommon, and a bit underpowered for a Rare.

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Of course, as with all such items, you know your party better than we do. If a character in the party is already more effective than everyone else, such an item may not be a good idea. Just because something is balanced in the general case, doesn't mean it's always appropriate at a given table.

Answer 3

You may want to take a look at the UA cantrip Mind Sliver (from Unearthed Arcana: Psionic Options Revisited). The spell description says (emphasis mine):

You drive a disorienting spike of psychic energy into the mind of one creature you can see within range. The target must make an Intelligence saving throw. Unless the saving throw is successful, the target takes 1d6 psychic damage, and the first time it makes a saving throw before the end of your next turn, it must roll a d4 and subtract the number rolled from the save.

This spell’s damage increases by 1d6 when you reach certain levels: 5th level (2d6), 11th level (3d6), and 17th level (4d6).

It has a casting time of 1 action. This would add balance by forcing the illusionist to spend an action to gain his bonus.

Answer 4

Add attunement and class restriction to balance that...

... but I'd bump the rarity if it were in my game.

Here's why I suggest that you modify it, based on a DMG item that is similar, but more powerful: the Robe of Archmagi. It is Legendary, requires attunement, and is only for Walrocks, Sorcerers, and Wizards. It increases Spell Save DC by 2. (Ref, DMG)

Unless you go "legendary" in rarity, I suggest that you drop the spell save DC to +1. (FWIW, the ring of invisibility is rated as Legendary).

If 'core' is your campaign's general power level

If you require attunement, restrict the class(es) for the ring, and drop the spell save DC to +1, a decent argument can be made for the rarity to be between rare and very rare. (Since the Robe has other features as well). Your PC being in the level range where very rare items occur (15) fits this item, so a conservative approach would be to make it very rare, gate it to sorcerer, and require attunement. Your PC will be happy and you'll be close to the core balance, if not in the sweet spot.

A word on Power Creep

There has been power creep, and it's well represented in Tasha's Cauldron of Everything as @BillyMailman points out.

Rod of the Pact Keeper, which you use for comparison, requires attunement and is gated by class. (While I have a suspicion that the Rod was a specific 'boon' for the Warlock class as a magic item since they have so few spell slots usable per rest, I can't prove it).

The Power Creep in Tasha's includes uncommon items that boost the spell save DC by one and that are gated by a single class and require attunement. I have awarded one to the Druid in my Saltmarsh campaign: Moon Sickle (even though I prefer not quite as much 'power' in my games). We'll see where this goes, they are at level 6 close to 7.

Since your question was "pre Tasha's" I'd suggest very rare + attunement to balance it at a +1 spell save DC boost. (But rare would also work, given the PC's level).

If the Power Creep in Tasha's is considered the norm for your table, all that your item needs is attunement and the class restriction to fit right in.

It is thus up to your 'feel' for power that will govern your final DM decision.

Your new item would look like this:

Ring of Channeling (very rare{or rare}, requires attunement by a sorcerer)
While you wear this ring, the spell save DC of your spells is modified by +1

If you want to modify the spells to +2, I will still suggest that you make it Legendary, like the Robe of the Arch Magi, and likewise require attunement gated behind a class, or classes. In that case, it becomes a reskinning of the Robe.

Again, while I suggest the 'less power creep' approach, based on when your question was asked, you can embrace the Tasha's Cauldron of Everything approach and make it a +2 and either rare or very rare, but I'd still suggest that you require attunement.

Answer 5

Yes and no

Whether or not it breaks the balance of the game largely depends on how you execute the solution, especially since you're in a homebrew setting. Just providing a flat increase on a character's spell save dc is naturally going to introduce power creep beyond what the developers intended and would throw off the balance that you are most likely accustomed to. However, balance is affected by many elements of the game, and by altering multiple elements at once you can still change it without breaking it. That is to say that you can preserve the balance by creating some sort of counter-balance to make up for the increased dc.

Easiest solution:

Essentially what you're talking about is specializing into a specific play style. It sounds like what your player is looking to specialize in is a greater consistency and dependability with their illusion-based spells. However, in order to avoid power creep in these kinds of situations, specialization must come with trade-offs. Groups I've run with have dealt with this in varying contexts from traits to class abilities to spells. This almost always requires some degree of tuning after implementation, but usually serves as a very stable platform for defining a play style.

An example specific to your situation that comes to mind would be giving them an item, lets say a circlet, that increases their spell save dc by two, but also shortens the duration of any illusion spells they cast. You are then giving your player the option to trade potency for consistency. Also, don't forget to justify this in the narrative!! This is D&D after all.

Here's a quick mockup of what that would look like... (feel free to use this if you'd like)

Crown of Thitus, God of Deceit

Attunement slots: 1

• The spell save dc for any illusion or enchantment spell you is increased by 2
• The duration of any illusion or enchantment spell you cast in halved
• Any illusion or enchantment spell you cast immediately ends after 1 hour

Thitus was once a mortal man, but was born with a dangerously cunning and mischievous soul. He had a natural talent for the arcane and reveled in conjuring grand illusions or bewitching others with fierce enchantments. But Thitus could never be satisfied. He easily grew bored, losing interest in his games as quickly as he created them. Yet his power continued to grow even as his interest in humanity faded. One day he decided to seek audience with the gods, promising himself that this would be his final game. And so called upon his cunning and illusions and enchantments one last time, and he fooled the gods into granting him ascension. He became one of them. Among their ranks he was established as the patron of tricksters and lies. Now he sits upon his illusory throne, watching humanity, waiting for someone worthy to take his place.

The main problem I've seen with this solution is the Swiss Army Knife effect, wherein a player or party builds a massive arsenal of magic tools like this that they hot swap between to gain the edge in every fight. This may not be a problem for you depending on you and your players' styles, but it is something to be cautious of.

Another (less easy) Solution:

You could give your player an item that simply provides a flat increase to spell save dc without any drawbacks, and instead implement a counter-balance by manipulating individual encounters. This is far more difficult as each encounter is going to be different and call for unique changes, and you must also take into account every other player in the party. For example, if you create a monster which deals damage to a random creature within thirty feet of it, this could harm not only the illusionist but also any other party member within thirty feet of it. There are a lot of moving pieces in this kind of solution, and though it gives you more control over each situation, it is much, much harder and more time consuming.