Sai'Uwm

This is the ancient language of the fae and forest. While traditionally an oral language it has often used the Knimwellit Symbology when it has been transliterated and set in stone. 
It is related somewhat to elvish and the primordial elemental tongues. They share some vocabulary with these languages and with the Druidic secret tongue. The most common creatures using this are the fae beings, Spotted Fae specifically have a very fluted intonation often perceived as musical, even when delivering insults. Many magical beasts that are able to learn a language find this one is the best suited to their diverse mouth structures, and each sound greatly different even when speaking the same language. Some of the more unusual types of The Touched will use this language for the same reason as other languages are hard to form and execute the intonation.

Phonology

Lots of hisses, clicks and growls are used compared to other languages. This works well with many magical beasts which are able to speak at least rudimentary forms of this language.

Syntax

Action and Descriptions are often interchangeable in order depending on emphasis being the first word. There is no explicit verb "is" as all those traits are just made as descriptions instead. It is possible to complete a sentence without a verb just as a statement of fact.

Vocabulary

Most of the language focuses on the natural world, so its vocabulary is often considered very specific in its niche. While the language has a much deeper vocabulary of smells, air pressure, rain, winds and breezes it lacks any hard numerical system. Instead of numbers they use general magnitudes and descriptions to describe quantities and volumes.

Tenses

There are only three tenses. Now, Recently and Imminent. The fact that most creatures that use the language have little interest in history or the future, it lacks a clear Future or Past tense instead relying on modifiers to indicate something that just happened or is imminent.