Any guesses on what Runestones and Arcane Orbs are?

This overlay popped up during a Duels run, and the only way I could get rid of it was to restart the Hearthstone client

They are the new Chinese currency for the game due in part to new Chinese lootbox laws. This is apparently a glitch people get when playing on the 2 other servers.

Thanks - that's very helpful context!

Quote From MisterFerro

They are the new Chinese currency for the game due in part to new Chinese lootbox laws. This is apparently a glitch people get when playing on the 2 other servers.

I find it funny that people are still calling it "new" even though it's almost a year old now.

Btw, they had to introduce this system because there it's illegal to directly buy lootbox. So instead they can now buy RuneStones(basically the Premium currency) which they can use to buy bundles or convert them into runestones (gold). It is stupid, but it works.