Hello. I think I've found out that the Explorer Ring(2 and 3) gives extra experience for every extra rune that's crafted. I was crafting Air runes and got 5xp per extra rune. So I think an extra rune gives as much xp as an extra essence, so with nature rune crafting or law rune crafting you should get even more XP. I used a tiara I'm asking you to verify this though. Just in case.