Dr. Mundo Build
Not Updated For Current Season
This build is designed for mid soloing. It might work if you don't mid solo, but it also might fail terribly due to lack of gold.
At the start of the game, you need to get Cloak of Agility. I like this because it usually allows me to crit and kill most enemies early game. I call itKamikaze Mundo. Use this strategy only if your enemy hasn't beaten you to the lane, or else they'll kill you.
First off, run up to the tower when you see the other champion coming. Let it hit you only TWICE. Any more, and you'll be killed. Now that you're at low health, run like hell, but don't use Ghost yet. Throw Infected Cleavers as you run. Soon, they'll be at half health and chasing you into the tower. They'll run, but now you use Exhaust. If they manage to escape alive, Ghost after them and kill them. Rinse and repeat the whole early game if they keep falling for it.
I classify the mid game as around level 11. By this point, you should have Force of Nature or almost have it. At this point in the game, you may be lacking a bit in power, but don't be upset by this. Just kite, kite, kite them. At this point in the game, resist the urge to enter team fights. Spend as much time in the lane as possible to farm mobs. You'll need the money badly, and you can keep the enemy mid busy to with constant pushes using Masochism and Sadism. Remember to be careful when pushing against a character like Amumu and other stunner, or you could start taking a lot of damage really fast.
Here's where Mundo really shines. There's really not much to tell here except don't get a bloated head and chase into towers and you'll do fine. Don't Burning Agony unless the people you're fighting are almost dead, it drains more health than it seems to, especially when you're under fire.
Good luck, and have a good time with Mundo, who thinks you're a big sissy!