So far haven't gotten to try every build i can think of for this hero but so far i got this he is great pusher and great damage and as a bonus he is fun to play and looks badass. :)

Pors
great pusher
very strong early game
good disable
great for team fights

Cons
2x melee = bad early game
other then that none for me

For masteries i did 21/8/1 for AD bonus and some armor with both exhaust and ghost buffed

Hi This is my first LoL build For Renekton, First i buy a Doran's shield and a health potion then you wanna try to get a partner that can harass the other lane so that you can farm minions at six u wanna try to get you and your teamate to try to kill the lane squishier hero in you lane so then if u get the kill or both of them you may want to go back and get your boots and maybe your kindlegem depending if u get both then you want to grab red and start ganking.

For items i went for attack speed / armorpen with some res/armor so i cna slice in adn ult to initiate a teamfight.