Druidic

Druidic is a language said to be developed by (or, more accurately, exists because of) the goddess Melora. It is the language of druids, and is also spoken by many kinds of nature beings such as treants, due to the language being based on the sounds and expressions of nature. Only druids and those devoted to druidism are meant to understand it, and so beings are "forbidden" from teaching it to non-druids. Druidic uses the Ogham script.