One of the many mysterious items that players get to find in Hollow Knight: Silksong is the Cogwork Heart, and one of the most mysterious ones at that. There are scraps of Cogheart scattered all around Pharloom, that get completed into a whole heart. Little does the game tell about how it gets used, but NPC hints from the likes of the Underworks Architect lead players down its path.
This guide summarizes using the Cogwork Heart, where to obtain each component, and what happens after completion.
How to Use the Cogwork Heart
In order to use the Cogwork Heart, players must acquire a sleeping sentinel located in the Cogwork Core. This is tied to the questline in which Hornet instructs that he learn three melodies.
Enter Cogwork Core by falling down the ground opening next to the melody chambers. On your initial visit, it is best to take the map on the bench in the left of the machinery room to use later for ease of orientation. From there, slide safely down through the vertical shafts evading traps and aggressive machinery until you notice an opening to the left.
Make your way through this area, then double jump to a hidden upper area. Break the trash blocking the way and make your way to the right until you find a robot trapped in a glass cage. Break the glass to interact with it.
Nothing happens if you fail to insert the Cogwork Heart, and the sentinel remains stationary.
If you insert the heart, the sentinel is revived and flies away. You will now see it again as it fights enemies around The Citadel, helping Hornet in some of its battles.
(Tip: Double Jump ability and all three Cogheart pieces are required to fully revive the heart.)
Cogheart Piece Locations
Cogwork Heart is created by gathering three Cogheart pieces, each behind a brief musical puzzle. To play them out, players will need to recall the ring of bells that chime, then ring them in the right order.
- Choral Chambers (Northwest) – Inside the highest areas of the Choral Chambers.
- Whispering Vaults – Reached through the Cogwork Core, on the path deeper into the Vaults.
- Memorium – The third and final work, available only using the Double Jump skill.
Upon combining all three pieces, Hornet gains the Cogwork Heart, enabling the ability to activate the sentinel in the Cogwork Core.
