I'm playing Mundo for a long time now and I like him alot, so I decided to do a Quickguide on him. He can be very very tanky and strong at the same Momentent, especially lategame.

Pros:
-Naturally tanky
-No Resources
-Can harrass the enemy very effectively (Q)
-Good at chasing and staying at high priority targets
-Lategame BEAST
-Lots of Sustain (Ultimate, Health Regen.)
-A lot of early damage

Cons:
-No escaping abilities
-Q is a skillshot
-Early vulnerable (bit squishy)

Most of the Time, I go with teleport and Ghost. I like Ghost, because with this spell, you can chase your enemy better, run away better and if you combine Ghost with Mundo's ultimate, it's just crazy how fast you get.

You can also take ignite instead of teleport if you think you can kill your lane opponent, but teleport is safer most of the time.

I put a point in Q lvl 1 to be able to last hit minons from a distance or to harass the enemy. Q has a very good Damage because of the % Health Damage. After that I usually max my W. Its is a good alround Ability, for pushing lanes, for farming and for killing ;).The reduced duration of stuns and slows on your W also helps too keep chasing somebody or running away from heavy CC. (Crowd Control)

Runes will be pretty standard Tank-Runes.
-Movementspeed Quints are very nice on Mundo, especially Lategame to just run into the enemy carries and to keep them busy or to synergize the Movementspedd with your ult + Ghost to just rush through Summoners Rift and hunt people down.
-Armor Yellows is a pretty standard rune on almost every champion. Its always good to have extra armor early game.
-Scaling MR Blues. Why scaling? Most toplaners do mainly AD damage. So you dont need that much MR early game, but later on in the game, you will be teamfighting and thats the point where you need some extra MR. Thats the reason why I like the scaling MR runes.
BUT: If your playing against a Vladimir/Heimer/any other AP toplaner or you are scared of their heavy AP Jungler (e.g Evelynn), maybe consider taking simple MR Blues with you.
-Hybrid Penetration Reds are amazing! Your W does magic damage and your autoattacks (in combination with your E) do very nice damage with a bit of armor penetration. I really recommend getting these Runes on Mundo.

This is just a Quickguide not a very detailed one, only for players who just want to see what Itembuild they should use on a Fulltank Mundo, what Masteries and so on. This is my first guide, I appreciate feedback and if you find some Mistakes or have some tips, write them in the comment section!!
Thank you for reading. :)