Hey, this is my first build here, but this build has yet to fail me. Unless the rest of your team has no clue what they're doing. Watch out for that. If at anytime you feel they can't do what they're supposed to be doing, buy boots in order to escape from being ganked. You can sell them later to finish off that Frozen Mallet. I would recommend going for Berserker's Greaves or Boots of Mobility. Either will suffice if you need to. I would go for Boots of Mobility because you don't need the attack speed that the Greaves get you. Plus, you get enhanced speed when you leave combat. Do not buy Banshee's Veil or Last Whisper. Neither are useful to you. When playing mid, poke. Poke like nothing else matters. Well, get minion kills when you can, but poke like it's your sole mission from God. Poke early, poke intelligently, and you should get 1 or 2 kills early game. That'll help you get an early start to your gold advantage. Also, make sure you have AMAZING map awareness. If you aren't aware, you will get ganked for sure and be killed early game. Assume your teammates are all idiots and that your entire enemy team is always trying to focus you. It'll help you stay alive and not lose any advantage you need to stay ahead in game. And try not to kill steal. It'll be tempting, but it's not a smart idea. Accidents do happen, but don't let them happen often.

These are important because you won't be buying boots. Buying boots may seem smart, but in fact may cause your build to slow down in effectiveness and reduce your ability to aid your teammates in team fights.

With runes, anything for attack damage, attack speed, or critical strike are all useful. Any are pretty much interchangeable, as long as they're Tier 3.

These are generally just safety masteries. They'll keep you alive and help you keep life so you live longer. Remember, more attack damage equals more life steal.

These are all for getting your attack damage up. I go for Bloodthirster first because you'll need to get those stacks early. It'll help you late game. If you die, go immediately for minions. Farming or jungling, both will help you. And Black Cleaver helps you take out health easy. Blus, once you've hit someone at least 3 times, it'll help for relatively easy killing with your ult. Also, if you are taking too much damage from someone, pick up Thorn Mail or a magic resist armor, whatever seems to be useful and will help you stay alive longer.

Obviously Piltover Peacemaker is what you want to max out first. Always go for your ult when you can. I go for maxing out the Net after because you'll need it to run away if you get ganked. That's also why you don't get boots and why Flash is a bad idea. Flash will get you killed. Ghost helps you run away.

This build is amazing for getting creep kills. Plus, when you get the Bloodthirster at max stack through minion kills, you can do some crazy damage to your enemies.