Hi, im pretty noob at creating builds but I think the best way to unlock renektons potential is with these items. Please read on through and give me feedback.

I give him the armor pen for the self-explanatory damage boost on his skills since he is a physical damage champion. Survivability with this offense build is key, with his armor seals and magic resist glyphs.

As this is a full offense build, I have my masteries as 21/0/9. Focusing physical damage in offense, and improved ghost with boosted experience in utility.

The key in this build is the offense. Utilizing those key B.F. items, I have maximized his damage output. No reason for offense when you cant live to reach the person, which is why i took leviatahn. My strategy with leviatahn is to try to kill steal champion kills as much as you can until you reach around 10 stacks. So what if your team rages? they'll thank you for saving them later in the game.

I say use the rush B.F. sword strategy so you waste no time getting all that damage instead of the effects i.e. armor shred from black cleaver. As using the first B.F. to upgrade I recommend Infinity edge as all your skills have on-hits and will give you insane killing potential, then next black cleaver for its synergy with ruthless predator's 3 hit with on-hit effects, lastly blood thirster for the survivability and longer fight time.

I take the merc treads to really give you that invulnerability to cc with the synergy of merc treads and cleanse. If the game lasts long enough, phantom dancers will be the best choice as it offers attack speed, crit chance, and movement speed to catch up to anybody.

Ghost is just an all around great spell for melee as you could escape or catch up to get in range. Exhaust is also a great spell for melee with its recreation. Reduces damage from abilities not to mention the slow and damage reduction from auto attacks, so you can just wail on them as they slowly walk away or save yourself from bursts that would otherwise kill you.

To tell you a secret, I have yet to buy or play renekton XD so these are all ideas, but I believe they could work as they all work in theory, try them out and comment please :)