I just want to say, for those looking for some fun, to try troll riven build.
I kept masteries and runes same for the most part because of the first part of the game in which you need to perform atleast decently.
Then comes the 2nd part. Instead of teamfights your job is to go all over the field, destryoing towers. Now here's the fun part, they'll often come 3-4 even 5 sometimes to gank you. With my items I have 453 speed, tenacity and 25% resist to slows. This combined with riven's internal abilities allows for alot of fun being chased all over the place. I have won many games with scores like 16-43 or 24-55 like this, they were winning teamfights but I kept poking them all over the place untill they were overwhelmed.
All in all, extremely fun games.