Runes appear to be split into 2 sub categories, Low Quality and High Quality.
Depending on the batch of runes you get from the temple when you head back to the rune menu and hit combine all the lesser runes will all be absorbed by the High Quality rune and will be used to augment the attribute on that rune.
A good example of this would be with the Mesa and Mountain Runes where Mountain would be the Low or Lesser Quality Rune and Mesa would be the High Quality Rune when you auto-combine them an upgrade to Mesa would be the end result.
The same would apply to say if you had a batch of Low Quality Runes consisting of Tactics, Mountain, and 1 Mesa Rune when you hit Auto-Combine the rune with the highest rating in this case being Mesa again would be the beneficiary.
But then again since there is no official word out there from uCool about how the runes work this is all conjecture.



