Would a house rule letting anyone cast their ritual spells as rituals be game-breaking?

Question

By default, there are limited ways for characters in D&D 5E to cast ritual-tagged spells as rituals. Either they choose a class with the Ritual Casting feature, choose warlock with the Book of Ancient Secrets invocation, or choose the Ritual Caster feat.

I'm considering a house rule that gives this benefit to any spellcaster. The rule would create some overlap between classes, adding some utility to a wider variety of party combinations (e.g., parties with a Sorcerer instead of a Wizard). The wording would be something like the following:

If a feature lets you cast a spell that has the ritual tag, then you can cast that spell as a ritual.

This rule should apply to ritual-tagged spells gained through a class, subclass, racial feature, or any other feature. It could also apply to spellcasting NPCs. But it should not apply to spells cast through scrolls or other items.

While this rule benefits some (sub)classes but not others, thereby shifting the relative power balance between classes, that is intentional. For example, this change adds versatility to Rangers and Eldritch Knights, yet it should not let them overpower Druids and Wizards, respectively.

My main concern is about mechanical choices that would significantly boost the character or party beyond what's expected for their level, such as somehow exploiting Magic Initiate to gain something much stronger than an ASI or feat.

So far I've considered possible consequences, and can't find ways it could unbalance or break the game. Am I missing anything? What possible exploits, if any, could be caused by this house rule?

Answer 1

My other answer discusses how this change effects the balance between the classes. In this answer I will focus on how it effects overall game balance and total party power level.

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This increases party options but not power level

Ritual Casting is mostly a utility feature; since it requires 10 additional minutes of casting time, it is completely useless in combat. What it does provide is the ability to: rest safely (alarm, tiny hut), communicate (animal messenger, illusory script, telepathic bond, magic mouth), obtain knowledge (many divination spells), and travel (floating disk, phantom steed, water walk) - all without consuming limited resources.

Four classes (Bard, Cleric, Druid, Wizard) get this feature at first level anyway, and if your party doesn't have one of those a variant human could take the Ritual Caster feat at first level as well. Given how readily available this feature is, it is fairly safe to assume a party will have this ability when designing adventures.

Given that adventurers are designed with this knowledge, a party without a ritual caster will be at a disadvantage to one that does not. They must spend limited resources (spell slots, hit points, 1/day abilities) to bypass challenges that could otherwise be solved with a ritual spells. Things like crossing dangerous terrain with floating disk, or finding the magic loot with detect magic are much more expensive without ritual casting.

Given how great the disadvantage is for being without a ritual caster most parties will choose to have one (or more). In particular it is one of the major strengths of the wizard with 22 ritual spells on their list. Your proposed modification would allow parties to choose from a wider range of combinations. By allowing, rangers, sorcerers and other casting classes to cast spells as rituals, you give them the added functionality of fulfilling the utility caster role.

A ranger will never be a better ritual caster than a wizard with this modification. They must have the spell known whereas the wizard can simply have it in their spellbook. Similarly, your modification is less powerful than simply giving out the Ritual Caster feat. The feat grants a ritual book to which you can add additional ritual spells, effectively increasing the spells known for a character, your modification does not do this.

Overall your house-rule allows more classes to serve in the utility caster role, increasing party options. But it does not allow the party to do anything they couldn't do already at the same level, had they simply chosen a different class. Therefore I believe this is a balance house-rule that should not adjust the overall power level and game balance, though it does somewhat reduce the opportunity cost of class choices.

Answer 2

My other answer deals with how this change affects overall power level of the party and game balance. This answer focuses on how it alters the balance between the classes.

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Rangers will love this. Slightly unbalanced.

Bard, Cleric, Druid and Wizard all already posses the Ritual Casting feature from 1st level. This house rule would have no benefit for them and therefore makes them weaker in comparison. Pure martial characters also gain no benefit from this house-rule. They have no spells (other than racial) and therefore have no ritual spells.

House-rules only benefiting a subset of classes/characters is usually a sign of unbalance. But we should also look at how much of a benefit is it really? And does it widen or close the power gap between classes?

By RAW this is a benefit that is worthy of a feat or an Eldritch Invocation. Both of those however, also grant the ability to learn additional spells. Your house-rule isn't as powerful. Though playing with this house-rule would make both those options significantly less attractive.

This house-rule is a buff for classes that have spells but don't have the Ritual Casting feature. The benefit will be limited by the number of ritual spells on the respective class spell lists. Rangers with 11 ritual spells on their list will benefit the most, Paladin (4), Sorcerer (4), Warlock (4) will all benefit to a lesser degree. The Arcane Trickster, Eldritch Knight and any other class with a spellcasting feature will also benefit. I am not aware of any races with a ritual spell but if they did exist they would benefit too.

Notably most classes that lack the Ritual Casting feature also have very few ritual spells on their spell list, compared to the Bard (8), Cleric (7), Druid (13), and Wizard (22). The exception to this is the ranger. Rangers have a lot of ritual spells on their list but relatively few spell slots and no Ritual Casting feature. Rangers are widely regarded as the weakest or the core classes however, so giving them a major boost in utility is not the worse change you could make.

Wizards are hurt by this house-rule as you are giving one of their key classes features to everyone for free. Rogues (other than Arcane Trickster) are also harmed by this change, as utility spellcasting allows others to compete in their skill monkey role. Additionally any class that lacks ritual spells on their spell list or has no spells is weakened by becoming less useful in utility roles.

Since your house-rule so heavily favours a single class, slightly favours a few others, and actively harm several classes, I would have to say that it is unbalanced. That said, ritual casting is not so powerful a feature as to be game-breaking, I would consider allowing this on a playtest basis.

Some things you may want to watch for during playtesting:

• Significant boost to Rangers' utility spellcasting
• Other casters stepping on the toes of Wizards
• Non-casting classes being even less useful out of combat
• Combining this with the Magic Initiate feat or multiclassing to gain cheap access to unlimited utility spells