Stuck in The Slab? Our guide reveals how to get the Key of Apostate in Hollow Knight: Silksong. Learn the path through Memorium to the Putrified Ducts and claim your prize.
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Hollow Knight: Silksong – How to Find the Key of Apostate
The world of Pharloom is filled with locked doors and hidden secrets, and the Key of Apostate is your ticket to unlocking one of them. This crucial item is needed to progress in a area known as The Slab, but finding it requires a journey through some of the game’s more challenging zones. This guide will provide the step-by-step route to locate the Key of Apostate and add it to your inventory.
Prerequisite: Acquire the Double Jump Ability
Before you can even begin this quest, you must have obtained Hornet’s Double Jump ability. This enhanced mobility is essential for traversing the large gaps and high platforms that stand between you and the key. If you haven’t found this ability yet, continue exploring until you do—it’s a core movement upgrade necessary for many late-game areas.
The Path to the Putrified Ducts
The Key of Apostate is not hidden in a random corner; it’s located deep within the Putrified Ducts. Here is the route you must take:
- Start at the Choral Chambers: Begin your journey from the Choral Chambers area. This serene, music-themed location is your gateway to the depths below.
- Descend into Memorium: From the Choral Chambers, make your way down into the Memorium. This area is likely a solemn, cave-like network filled with echoes of the past and platforming challenges. Use your double jump here to navigate its verticality.
- Enter the Putrified Ducts: Continue pushing downward from Memorium until you reach the entrance to the Putrified Ducts. As the name suggests, this area is a polluted, hazardous network of tunnels. Be prepared for environmental dangers and new enemies.
Locating the Key of Apostate

Once you are inside the Putrified Ducts, the search begins. The key is not in plain sight.
- Thorough Exploration: The ducts are a maze. You will need to explore its various passages, which likely involve using your double jump to access higher ledges and alternate paths.
- Look for a Distinct Chamber: The key is often found in a secluded room or at the end of a specific branch of the tunnel network. It may be resting on a platform, protected by a minor enemy, or hidden behind a breakable wall.
- Claim Your Prize: Once you find it, simply walk up to the Key of Apostate and interact with it to make it yours.

Using the Key of Apostate
With the key now in your possession, its purpose becomes clear. Return to The Slab. somewhere in this area, you will find a locked door or a peculiar seal that reacts to the Key of Apostate. Use the key on this lock to unlock new pathways, discover hidden lore, and find valuable rewards that are essential for your adventure.
Pro Tips for Your Journey
- Come Prepared: The path to the key is long and fraught with danger. Ensure you have a full spool of Silk and plenty of healing items before you embark.
- Map It Out: Purchase the map for each new area (Choral Chambers, Memorium, Putrified Ducts) from Cornifer as soon as you hear his humming. This will make navigation significantly easier.
- Check Your Abilities: Beyond double jump, other abilities like the Silkspear or Dash might be needed to defeat enemies or access certain parts of the Ducts.
The path to the Key of Apostate is a test of your platforming skills and exploration prowess. By following this route through Memorium to the Putrified Ducts, you’ll unlock yet another piece of Pharloom’s vast mystery. Happy hunting!
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