The Hollow Knight Silksong Apostate Key is the last key needed for The Slab, and you'll have to scour an unforgiving area to find it.

Silksong fast travel utilizes a very cute new friend to help you get around Pharloom fast, as long as you can find and unlock stations.

Here's exactly where to find all Silksong Pale Oil locations to complete Pinmaster's Oil and deal increased damage against tough enemies.

Here's where to find Silksong Simple Keys, where to use them, and all the shortcuts and rewards that lie hidden behind those locked doors.