I've been playing Heim quite a bit lately, and have grown accustomed to his weaknesses. With a normal build, Heim is excessively good at pushing early-game, but excessively gankable as well. Late-game, he's next to useless, even when building all AP for damage output. The main problems I have when playing him are that his basic attacks are useless late-game (especially for team fights) and he's too slow to run away, kite, lure, or gank effectively. This build Makes up for those problems. With this setup, he's still a great pusher for early-game, while being able to survive late-game. The biggest downside to this build is that his mid-game damage isn't desirable. The biggest problem you will encounter with this build is if your team is too fast and/or doesn't have much CC other than you, as either of these make you too focusable, in which case you should think about getting some heavier items like Thornmail perhaps instead of Malady.

This build is effective mid, but if your team doesn't have a Jungler who can gank for you or help when you're in trouble, you're better off letting someone else get the farm. The biggest reason that this build is better than most for mid is that you're less gankable with the speed and DPS you have. I suggest using your Turrets as often as possible, even using them to ward when you're expecting a gank. Map awareness is key, however, because you're still not that fast and are still gankable.

Early game and mid game, use your turrets often, remembering to use them against turrets whenever possible. When soloing a heavy damager, make sure to stay behind minions and save your stuns for when you need to run. I always try to use my rockets while circling around to the side of the enemy minions opposite my own turrets in an attempt to hit the enemy champion.

For team fights, you're still not that much help, but you should be able to survive better using this build. I try to lay down turrets early at the front of my team, especially if it's an in-lane fight, or use them on the edge of the Jungle for extra awareness from flanking enemies. once you've lain them, try to use your rockets and stuns on the enemies assassins or whomever's lowest health that your team's focusing. Other than that, make sure you're always in the middle of your team when possible, drawing little damage but still being close enough that your abilities can be used efficiently.

The basic strategy for regular lanes is the same. The only changes I make are using my turrets more often in bushes for wards while they're still close enough to hit minions and to build boots and PD earlier, especially when laneing against assassins. Try to stay towards the wall, especially when laneing with a tank in order to stay out of gankable situations.

Farming in either lane is mostly done with your turrets early-game. Once your AS is built a little bit, start focusing minions your turret(s) are not focusing, as you'll burst through waves easier and be more likely to get the money. Also, use your Promote whenever possible, especially in other lanes. I can't count the number of times I've destroyed a tower in another lane or even while I'm dead because my promoted minion got the kill.

When defending a tower, make sure to stay within it's range so that it's healed by your passive, and Place your turrets just outside its range. This way, you can get most of the gold without the tower KSing your minions. Try to focus the mage-minions and let your towers attack the close-range-minions as you'll cut down on the time it takes to clear waves this way, and because of your placement, you'll still be in range of the tower and your turrets, healing all of them, while still getting at least most of the gold from the lane.

HEAR ME OUT BEFORE YOU DOWN-VOTE!

Please don't just troll-vote this down. If you're interested, try it out. If it doesn't work, THEN give it a down-vote. Way too many people reject builds because they're different or they don't like the champion. This is meant to be a serious build, which I actually use on a regular basis. I've found that my games are about 50-50 with this build. Either I do really well or I got destroyed, there's not much mid-ground. I'd love to hear your non-rage feedback or suggestions for improvements :D