Proto Vauqun-Adzovъd

Summary
Descendant of Proto Csillan. Basically Csilla's equivalent of PIE. Unlike PCS, PČN was actually reconstructed. In certain places I'll use blue writing to highlight etymology information that couldn't be reconstructed yet is known to me 'cuz I made the lang :P

Vowels
As can be inferred from the graph above, most vowel qualities distinguished length and some nasality, while only two have only one form which makes sense when you consider that those two qualities only existed as the product of umlaut that did not affect long vowels (and all nasal vowels are long.)

Phonotactics
Legal Onsets: C, [+fricative][+plosive], Cj

Legal Nuclei: any vowel of any quality or length- though nasal vowels cannot occur before a complex coda (2+ consonants)

Legal Codas: [+consonant -nasal], [r, w]C, and of course nothing

Legal Middle Clusters: any coda + onset, unless it breaks the following rules: Any combination of obstruents must agree in voice: if a cluster is created that does not agree in voice, the second obstruent determines the voice for the whole cluster
 * fricatives cannot follow nasals
 * the only plosive + plosive combinations allowed are geminates and those beginning with a velar, otherwise the initial plosive spirantizes: /p t b d/ > /f þ v đ/

Morphophonemics
Vowels underwent many shifts under certain conditions, with varying regularity:
 * Vowels raise before r, w, n and m in closed syllables (-r also makes the vowel long if it isn't) /y e æ a o/ > /i y e æ u/ -highly regular in short vowels, less common in long vowels (particularly in declension & conjugation when one of these sounds is made to follow a long vowel)
 * Vowels of any length nasalize before n and m, after raising /æ e y i u/ > /ą ę ę į ų/, 100% regular before split
 * Vowels lower in any other closed syllable /i y e æ u/ > /y e æ a o/, same regularity as first rule
 * Short vowels become long before voiceless fricatives at the end of a word
 * Ablaut triggered by a long vowel (except ȳ) following a short one. Fairly regular; does not occur, however, when the vowel was elongated due to a productive sound change at a morpheme boundary, ie hito- (to be) + -nzy (infinitive ending) > hitųzy, not *hütųzy
 * Fronting umlaut (before ī, ē, į or ę): /a æ o u y/ > /æ e ö ü i/
 * Rounding umlaut (before ō, ū or ų): /a æ e i y/ > /o ö ö ü ü/
 * Open umlaut (before ā or ą): /æ e i y u/ > /a æ e e u/
 * Ash umlaut (before ǣ): /a æ e i y o u/ > /e e y e ö o/

There were also a few grammaticalized consonant shifts which are discussed in the grammar section.

First Declension
The first declension, also known as the "thematic" declension, contains entirely animate nouns ending in any short vowel except æ or u. It shows a great deal of variation depending on the root vowel, as well as a consonant shift to further mark the oblique plural cases. The consonant shifts are as follows: These shifts happen to the consonant right before the root vowel and they occur in every plural case except the nominative.
 * [p t k b d g] > [f þ h v đ ɣ]
 * [f v s z] > [þ đ þ đ]
 * V[n m] > [nasal vowel] + [s]
 * [r] > [ɣ]

I'll add some examples of declined nouns when I feel like it :þ