Rune Rock
From RoR Wiki
The Rune Rock is a unique item that can be found in-game.
Aqquiring
Acquiring a Rune Rock requires the completion of specific Life Events, of which the first is "Return to Ekrund". There could be more Rune Rocks available in future Life Events.
Used for
This item might look less valued than it actually is. Hold on to your Rune Rocks, keep them safe, defend them with your life.