~I figured i'll break even make around 21M Airs (from Level 70, which is where i am now.)~

 

 

 

~I want to know if Natures or Laws are faster. I know i'll lose a ton more on them, though.~

 

 

 

~I can sell 21M Airs for 315M, at the least, so if i spend 100M on essence, i'll break almost even.~

Check this post on the official forums: 22-23-479-43652376

 

 

 

And I'd like to give you some advice: getting 99 rc from 70 in one row will take incredible long, I won't say it's impossible, but you need a lot of dedication for it.

After 91 runecrafting, you could join the world 36 double natures for around 50k exp on average. Quick find code: 37-38-29-44487588. It doesn't cost anything, but you don't gain any cash either.

But before that, the best is 66 or 99 Laws or 16 Airs.