Afdl Ttbyq Radyw Byn Sbwrt -

The Void answered with a sound like breaking childhood. Sbwrt then cut that sound in half, and the two halves became a door. Beyond the door was a garden where every forgotten name grew as a flower.

a→s, f→g, d→f, l→; (not letter) — fails. afdl ttbyq radyw byn sbwrt

Let's test (a↔z, b↔y, etc.):

a→z, f→e, d→c, l→k → “zeck” ttbyq → s s a x p? Let's do properly: t→s, t→s, b→a, y→x, q→p → “ssaxp” — no. The Void answered with a sound like breaking childhood