This is built around the fact hat Mundo has outrageous amounts of HP. While his offense is not very powerful on his own he should be almost unkillable. You can be an off-tank or initiate without any problems. While Mundo has his ulti up he's not only a regen god but can run fast, combined with ghost, if things go bad, run!

Any comments are greatly appreciated. Please read fully and thank you for any help!

Well, I decided to make his masteries very deep into defense. I find that bumping his attack is not very efficient for my taste. I'm sure some will disagree. Since I'm going for outrageous amounts of HP, this seems the best way to do it.

HP Quinns
Dodge Seals
Cooldown Glyphs

Now, Marks. I already have attack speed Marks. This is why it's in the build, because it's what I'm stuck using at the moment. Ideal scenario would be either straight HP marks (31.23 HP at start of game) or per level (87.48 at 18). The attack speed isn't terrible obviously but goes against my build purpose.

Pretty obvious I'm going for HP. I ended it with a mallet...but honestly by the time I have the 2nd warmogs it's usually over. I start getting that S.V. by getting a regrowth pendant first. I find it's better than a straight HP item like Ruby. I also get a HP pot.

Pros:
Should never die. If you do the other team should lose more than you did. You can run from almost anyone with Ulti/Ghost combo up to run from gank.
Early game harass is awesome using cleaver. You're HP regen will keep you up without any issues. Use bushes, please!
Cons:
Lower damage output. Cleaver is still pretty awesome but generally without items/masteries to support dmg it's lower.