Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Renekton its a melee carry ad dps, it is difficult to manage him, specially is you dont make a good job in early game.
Armor Penetration: 3 of his skills have ad damage so 9 armor penetration marks would be great for him.
Dodge: In your masteries you got 2% dodge chance plus this runes would be a great combination including the boost of 10% speed everytime you dodge.
Magic Ressistance per level: You're a melee champion so you need some MR to stay alive in battle as long as you can.
Health: 3 of these quintissence would be great for the early game its good always to have more health than the other team.
As youre a melee champion you will need to survive during battles and do as much damage as u can.
Doran Shield: This item with a pot would be great to stay in line and dont go back, to creep as fast as you can.
Mercury treads: I think you hate stuns, slows, taunts as me so this would be great to stand in battle and also to run from them.
Ghostblade: Armor penetration + Damage + Attack speed + Movement Speed works perfectly with Renekton.
Last Whisper: 40% Armor penetration for those tanks hard to kill
Frozen Mallet: Excellent health afford + a little damage and the possibility to keep following your enemies and slowing them :D
Impaler: You got some Health now its time for some damage and armor for survavility.
Bloodthirster: More damage and lifesteal :D