Philosopher's Stone

Within the mod, the stone is only found in worlds where the mod is installed, and it can be crafted there. Its recipe is kept secret until the player has discovered it, and once known it appears in the REI recipe book. The mod groups several effects under the stone's legend: it can turn copper into gold, it can be used on certain animals to make them juvenile, and it has a healing property that keeps the player's inventory intact. Some of its uses touch work horses, villagers and hostile mobs.

The stone is tied to the elixir of life, which is linked to rejuvenation and to the long pursuit of immortality. The mod's potion of healing is the centre of that link, and only that potion works with the stone. In hardcore mode the mod can make a player immortal. The author notes that the mod could not be tested for immortality, because a Minecraft player is already immortal in the normal sense of the game's rules, so the claim should be read as a feature description and not as a tested result.

Installation needs Fabric API on Fabric. Installation covers the server and each player's game. It is published for Fabric and NeoForge across 20 release versions, 1.20.2 – 26.2, and is released under the MIT License, which makes it open source with public source code on GitLab and GitHub.