Deep Speech
From Arelith Wiki
Deep Speech is a catch-all term for the languages of aberrations, of the stars, of leviathans- any and all alien forms of communication whose origins lay outside the intellectual and cultural egoplex of mortals. They have no Toril- or planar-native scripts of their own, but can be transcribed in a variety of scripts.
One of the more notorious examples used the Espruar script, as it was first transcribed by the drow due to frequent contact between them and the many aberrant races they lived in relatively close proximity to within the Underdark.
On Arelith this language is known by: