Governing and Tuning Stones are the new seasonal items added in Diablo 4 Season 3 that help you control your robot minion or Seneshchal companion the way you want. This will be a “pet”, but someone who will directly or indirectly help you in combat. Here’s how to get the most out of this new mechanic to make your companion as powerful, customized, and suited to your class/build as possible.
Seneschal Governing/Tuning Stones – How to Get and Upgrade Guide | Diablo 4 Season 3
Governing and Tuning Stones are item drops that you can obtain after completing Vaults, the new seasonal dungeons in Season 3. Blizzard's blog also notes that you can also get these stones "elsewhere in Sanctuary."
Vaults are the primary locations to obtain them – they are treacherous and deadly areas filled with elemental hazards created by Zoltun Kulle and Ayuzhan. Within these dungeons you will find a new family of monsters – the Constructs.
Nightmare Vaults are unlocked at World Tier 3. They are similar to Nightmare Dungeons, but differ in that they contain Constructs and Hazards, in addition to the Wardwoven Chests.
