This is my Mundo build. I'm going to make this brief, with only the explanation one really needs to pwn with Mundo. Mundo can be really tanky, or you can build him DPS - This build is basically both because you stack health and then get Atmas, which skyrockets your damage.

IMPORTANT NOTE: the build order isn't really what you want to be going.... it's situational. Get all the items through Warmogs, but after that grab a force of nature if the team's more AP.

Slam your Q into the enemy as much as possible. I KNOW I KNOW, you can stop QQing at the fact that you dont have a potion to start, but whatever, you dont need one. just be safe and dont die, and dont play too aggressively until you get ur ult, when you can almost completely heal every minute or so.

Anyway, if you really feel like ur gona scrape, go for snowball. it might be a good idea.

Honestly there isn't much more to say. use Q frequently, and dont be afraid to have W on a lot.

I started playing Mundo like yesterday and am goin like 20-somethin with him constantly.

IMPORTANT: mundo is broken on 3v3, so have fun.