Like Weapons, they have a tier system as well, with Greater Runestones providing a larger effect than it's regular and Lesser counterparts. You'll be able to find Runestones by defeating Enemies, in chests, or by asking a blacksmith to craft one if you have the correct diagram unlocked. There https://stepheniqvyc.theblogfairy.com/35938083/um-imparcial-view-of-the-witcher-3-wild-hunt