About the build:

Build is selfmade (I dont know if there's an identical build)
The build gives the summoner a great early game with a big amount of HP regen and some flat health runes, can hold lane against most champs. The builds have a downside tho, the
not specified Armor build, exept some Marks, that can be a problem with champs like: Tryndamere, Yi, Xin Xhao etc.
In most games with this build the chat has been spammed with things like: "God Mundo you imortal purple f**k" (Not my words)

Pros and Cons

Pros:

Great minion farming
Tons and tons of Health
Lots of Health Regen to stay in lane solo
He is freakin' Purple
Great for jungler ganks

Cons:

When ult is on cooldown its hard to escape ganks
The basic attack in early game

Masteries:

Health:
Health Regen is the keyword of a good early game so i maxed Vigor. Flat health isn't bad either therefor i maxed all health masteries availible. Thats lays the ground for an awesome solo top lane.
And of course Juggernaut for an imortal Dr. Mundo
Movement speed:
Movement is an important mastery for Mundo as it gets you quikly back into lane when recalled. Another thing about is getting out of ganks too.

Summoner Spells:

The summoner spells is in my eyes free of choise well Flash or Ghost is important tho because he has a hard time getting outta ganks.

Farming:

Mundo is a very good farmer i basic but a few tips is:
-Try to last hit minions in early game instead of wasting all you health on Burning Agony
-Use Masochism to get the tough minions down before the kill all yours.
-If you end up against a long range champ use your clever to last hit
-In late game... Go berserk

Harrasing:

Use your clever to harras the champ/champs in your lane. Wait in bush, cast infected clever (if it hits) run out and use Mansochism to damage down.