Every language character optimization

Question

I've been theory crafting how to design a linguist character who is able to read and speak every language. I managed to accomplish this with a level 20 wizard who takes Signature Spells on tongues and uses Spell Mastery for comprehend languages.

Is it possible to do this at an earlier level (i.e. the earliest possible level) with different character options to pick up Thieves' Cant with a 1-level dip in Rogue? Are there any other languages I miss out on with my build that another could pick up?

Notes:

• No telepathy since the character concept involves serving as a high order translator at political conclaves , for example. Similarly, the character has to presentable acceptably as a grand translator (I don't know if that will be a problem for some options, but it's worth keeping in mind)
• Learning enough to exhaust the list of languages is not an option since there are way too many possible languages for this to be reasonable (I'm counting monstrous languages too, and WotC keep adding more with each adventure module)
• This has to be accomplished without expending limited daily resources like my spell slots
• Only one attunement slot can be used
• Bonus points for finding a way to write the languages too.
• Please only use official WotC content (i.e. no homebrew or playtest material like Unearthed Arcana)

Answer 1

Monk is the Way

I did not see anything in your initial question that would prohibit it, but a 13th level Monk with the Tongue of the Sun and Moon trait would meet two-thirds of your criteria very well (being able to understand and speak all spoken languages).

The final third (being able to read all spoken languages) can be easily accomplished by a 1 level dip into Bard or Wizard; taking the Comprehend Languages spells; and using the innate Ritual Casting ability of those classes to cast the spell.

Alternately, you can simply have your Monk take the Ritual Caster feat and pick one of those classes for it.

One other thing you could do to gain Comprehend Languages is find a Helm of Comprehending Languages, which will permit you to cast the spell at-will. As an uncommon magic item, this may be very achievable in certain settings.

Answer 2

Monk 13/warlock 2 does what you want.

This multiclass can understand all spoken languages, can read all writing, and can speak to anyone that understands a language. This does not use telepathy, does not consume resources, and does not teach you any languages.

A level 2 warlock can get the Eyes of the Rune Keeper invocation:

You can read all writing.

And a level 13 monk gets the Tongue of the Sun and Moon feature:

Starting at 13th level, you learn to touch the ki of other minds so that you understand all spoken languages. Moreover, any creature that can understand a language can understand what you say.

However, I do not know of a way to write in any language without consuming resources.

Edit: about thieves' cant

As Joshusmu said, you can also take one level in rogue for thieves' cant, but I don't think its necessary for a translator. Thieves' cant is not a language, it's:

a secret mix of dialect, jargon, and code that allows you to hide messages in seemingly normal conversation.

Therefore, there is no scenario where you can't communicate with a creature because you don't know thieves cant:

• If a creature knows any language, you can already communicate with it through Tongue of the Sun and Moon, whether or not they know thieves' cant.
• If a creature does not know any language, you can't hold a conversation with it, so you can't communicate with it through thieves' cant.

Moreover, thieves' cant's sneaky uses shouldn't be acceptable for the same reasons David Coffron does not want to use telepathy.

Answer 3

A character who can change into either a Deva or Couatl or enslave one

Devas and Couatl's have the feature

Languages all

which bypasses all of the requirements.

So any 17th level spell caster (Bard, Warlock, Wizard) with True Polymorph can turn into one of these two creatures indefinitely.

You may only need to employ one of these spellcasters as a once off to apply it to one of your servants.

Alternatively any 9th Level Wizard, Druid or Cleric with the Planar Binding spell could bind a Couatl or Deva into it's service and make use of that creature to function as the orator. (Note: finding and restraining one for the full hour casting time of planar binding may be difficult)

Planar Binding has a duration of 24 hours.

Answer 4

A warlock can accomplish those same spells as your wizard by level 5

Since warlock spell slots recharge on a short rest (not unlike Signature Spells) using comprehend languages and tongues as a warlock dodges the limitation on daily resources.

Pact Magic

[...]

Spell Slots

... You regain all expended spell slots when you finish a short or long rest.

This lets you get your multiclass in rogue for Thieves' Cant by level 6 (assuming you have 13 Charisma and Dexterity)

Eye of the Rune Keeper

As a Warlock you could also pick up the Eye of the Rune Keeper invocation (if no others are pertinent) so that you wouldn't have to waste resources on comprehend languages.

You can read all writing

Answer 5

Be a 9th level cleric, with a 2 level dip into warlock (with potentially a 1 level dip into rogue for Thieves Cant)

Once a cleric reaches 9th level they can cast the 5th level spell Hallow on a location.

One of the options Hallow gives is:

Tongues. Affected creatures can communicate with any other creature in the area, even if they don't share a common language.

Hallow lasts on a location, within an up to 60ft radius, until dispelled.

Additionally, Hallow’s text states (emphasis mine):

When a creature that would be affected enters the spell's area for the first time on a turn or starts its turn there, it can make a Charisma saving throw, On a success, the creature ignores the extra effect until it leaves the area.

The fact that it can make a saving throw suggests a choice, meaning that the creature can choose not to make the saving throw.

The 2 level dip into warlock is to get the Eyes of the Rune Keeper invocation to

... read all writing

As a note though, Thieves Cant isn’t really a language, but a way to give a secondary hidden meaning to an otherwise perfectly understandable phrase.