What Heart of the Immovable King Does

Heart of the Immovable King makes the Pal's SAN drop 20% slower — the top of the standard sanity family, above Workaholic (-15%) and Positive Thinker (-10%).

Sanity drains mostly at base while Pals work, so this is the ultimate worker quality-of-life slot: it single-handedly covers the extra drain from Demon’s Hand with room to spare, and it's the passive that makes a permanent Insomnia night crew genuinely sustainable.

How to Get It

There are two routes. It occasionally rolls on wild Pals, but as a rare-weight passive it's roughly 20× less likely than a common one. The reliable route is Disposable Implant: Heart of the Immovable King , applied at the Pal Surgery Table — the surgery is free, but the implant is consumed.

The implant comes from the Ancient Relic Recycler : every recycled Ancient Relic of any grade rolls one disposable implant from a 16-implant pool, so it lands at 6.25% per recycle. See the Ancient Relics guide and the implants guide for details.