This is more for my personal use but feel free to comment/share/improve upon my guide.

These are my generic mastery/summoner spell builds. Those ohh **** no one on my team pick a [insert role here] champion and I need to grab one quickly! These builds help me make those split second decisions where I need to change my champion with 10 seconds remaining to choose. I'm level 29 and have yet to dive into the ranked queue so these are solely based off my blind pick needs.

In case the champs were not self explanatory:
Graves = My generic AD Carry build
Karthus = My generic AP Carry build
Udyr = My generic Jungler build
Olaf = My generic Bruiser build
Janna = My generic Support build

Again these are my personal preferences for those roles when I don't have a specific page built for said character. NONE of these builds are character specific and I understand that while they will not be the best build for every character in said role they will certainly get the job done.

Thanks!