Avacyn sits next to 5 phonetic neighbors — Avacin, Avasin, and Evalyn are the closest matches by sound. Most share Avacyn's Invented (Magic: The Gathering)-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"angel of hope, protector"
"merciful, gracious"
"airy, free-spirited"
"God is my lord (El + Yah element)"
"official of Yah"
"quiet, still"
"God is my refuge, noble"
"God is my light"
"Lord, have mercy (liturgical phrase)"
"gift of God"
"combination of Zena (life/hospitable) and Layla (night/dark beauty)"
"clearing in the woods"
"gracious, favored by God"
"God is gracious"
"modern invented name combining dale and lynn"
"pearl (via Mia/Maria)"
"festive occasion, day of rest"
"divine, pure"
"arc, curve, arch"
"life, living"
"precious gemstone, treasure"
Similar sound: These names share phonetic patterns with Avacyn — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Invented (Magic: The Gathering) origins, giving them the same cultural heritage as Avacyn.
Rhythm: Avacyn is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.