well ive actually thought of this alot, well first off to be able to get a propper kill using leblanc you will need to be atleast level 4+ (thats the minimum level) where i see her being able to get a kill over another decent player. The reason i see this is that she needs to atleast have all skills up and sigil higher than a mere level one to produce some dmg with or without some early game runes; if you look at my guide i actually recommend playing a defencive style early game which does not suit early game runes. Using this guide kills will come after level 6 onwards and by this time i dont see early game runes very effective anymore and late game runes actually more effective.

As for the build..... well you do need to put into concideration that most builds are some what similar, for example most builds for mages contain sorcerer boots, arch and deathcap. Have a look at the top build for leblanc and you will see we have the same build except for me having zhonyas and him rod of ages

Thank you for your comment but please read the FULL guide which covers play styles.

I dont think rune are good for leblanc since she's a pretty early game character/killer you want to get her some early power. For the rest it's a common ap build nothing out of the ordinary.

Thank you :) and yea getting potency could be a good idea. I tend to get late game runes all the time just for the overall extra stats.

This is actually the build I always use, except for the runes. I get Potency.
I guess you read my mind!

+1 Nice build.