Everyone in Diablo 4 season 3 will get their very own robot companion that you can equip with all sorts of powerful skills and then modify with "tuning stones". You can read through a list of these new seasonal items in Blizzard's blog post, but two of them are left blank and said to be talked about "in hushed whispers" by Sanctuary's scholars.
In an interview with PC Gamer last week, Blizzard said these two companion tuning stones will mirror the power and rarity of Diablo 4's Uber Uniques and will give you "bragging rights" if you find them.
