As with every build, it depends a lot on the game. I have found myself requiring a Thornmail in order to stay in combat with characters like Master Yi, Warwick, and Tryndamere. Many people like tank items on Renekton, but I like defensive masteries instead. That way, I can focus on a damage output. Frozen Mallet is a good enough item for the extra health, though, depending on the game, you may want to grab a Sunfire's Cape. If I have the time and the money, at the end of the game I sell Doran's Blade. Again, what you buy next is entirely dependent on the game. You may want to get a tanky item at this point, or, if you have a good tank, grab Bloodthirster's or Madred's Bloodrazors.

This build isn't perfect, but I can tell you honestly; I am not very good at this game. I love it, but I am not very good at it. This build has led me to incredible victories, and I hope you find it equally useful. Enjoy, feel free to ask questions about strategies and such.