I believe that tertiary Runes are a good idea, so that we can select one Rune (not a keystone) from a third Rune Path. For example: I would select Domination as my primary Rune Path with Dark Harvest as my Keystone, along with Cheap Shot, Eyeball Collection, and Ultimate Hunter; Sorcery would be my secondary Rune Path, with Transcendence and Gathering Storm; and Inspiration would be my tertiary Rune Path, with Cosmic Insight.
Adding a third path, while it seems like fun, would cause a massive amount of gameplay imbalances, even more than what we already have.
It’s not a BAD bad idea, it would add some unique flavor for sure, I just don’t think it’s something Riot wants to touch right now. The potential for certain combinations to achieve sheer brokenness is high and would just be another mountain to overcome as far as balance is concerned.. [sg-lulu]
Besides the balance issues highlighted by Boltonator, the decision of choosing from 2/5 was a conscious decision, and the third minor Rune might actually add TOO MUCH choice, taking away from the decision-making involved.
