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Basically, I try to show how Mundo's item build is adaptable based on what your enemy team is. Spirit Visage is of course a must, and then you can go Stark's Fervor->Frozen Mallet for raw damage Mundo or go Aegis of the Legion -> Force of Nature/Sunfire Cape for unkillable stays-in-battle-forever Mundo.
Skilling, I suggest going Q/E/E/Q/W/R for your first 6 levels. Two ranks in Cleaver is a must as 1 just isn't good enough for helping you get last hits on creeps and the damage it gives over 1 rank makes it something enemies will actively try to avoid whereas only 1 rank does pitiful damage beyond level 3. Burning Agony does too much damage with even just 1 rank to ignore before everyone starts rolling around with their ultimates. Beyond that, max Masochism, then Burning Agony, then finally Cleaver.
I also discuss briefly lane partners. Basically, my top two to roll with Mundo are Taric or Nidalee. (I always recommend playing Mundo with a healer just so that they have someone with a Spirit Visage to doll out ridiculous heals to.) I also suggest a couple people to laneswap against (basically anyone with a way to stop your health regen). That entire section will grow eventually but that's all I've got on there for now.