Many games are won by what happens before the 15 minute mark. This build is for early aggression and will allow you to get some easy kills, as well as power enemies out of your lane. Kills are even easier once you get your ult. I use this build in a duo lane and it works very well. The masteries/runes/summoner spells are entirely up to you, but I use the ones I do for a reason, and they work. Clarity is taken because I sometimes miss kills because I run out of mana at a critical moment. Ghost is taken because along with body slam and cooldown reduction, you have extreme escape/chase power. Mana regen runes are taken to allow for extreme enemy abuse and exp denying in the early stages of the game. They also make you feel better about missing a barrel roll here and there (costs more than his ult).