This Mundo guide is very helpful if you want to be the team tank for solo top lane,also if you want to spam cleaver without killing yourself, and run into team fights healing like never before.

Infected Bonesaw Used to harass the enemies early game to poke down their health, also used to slow anyone who tries to run away from your team.
Heart Zapper Used to farm and Deal AoE damage, you are supposed to keep this up at all times in a team fight to hurt everyone.
Blunt Force Trauma Increases AD for a couple of seconds best used for melee combat but it isnt the best choice to upgrade early game if you are a tank.
Maximum Dosage Used to regen all of your health back up if you have all of the right items, so it is best used in the team fights when you are taking too much damage, but when you have Ignite on you it heals much less and you have a better chance of dying.

Pros:
Very tanky
Extreme health regen
Alot of movement speed

Cons:
Always being called op
Easy to kill early game

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For marks i use Greater Mark of Magic Penetration if you would like a bit more damage with your spells early game but you can trade it in for Greater Mark of Health for extra health early game.
For seals i use Greater Seal of Resilence for the extra armor but you can also use Greater Seal of Magic Resist if your against AP champions alot.
For glyphs i use Greater Glyph of Vigor because the goal of a tanky mundo is health regen so you dont really need to change it.
And for Quintessences i use Greater Quintessence of Health for extra health but you can also use Greater Quintessence of Movement Speed for chasing people down.

For mundo i use 0-22-8 masteries to be as defensive as possible. The main talents you HAVE to have are Vigor Durability Veteran's Scars and the movement speed talents but other than that they are all up to your preference. You can have more points in offence or utility if you like more damage.

With mundo try to get as many last hits as u can,by using Heart Zapper, unless you get a heart of gold then you can just stay back and spam your cleaver at the enemies and let your ad carry get the last hits. If you are solo top you need to try to be as defensive as possible and throw cleavers at the minions and enemies, but if you end up being solo top i highly recommend the heart of gold for the health and extra gold.

With tank Mundo you try to max out Heart Zapper and Infected Bonesaw for harrass and AoE damage but if you want to have more damage you can get points in Masochisom earlier, and increase Maximum Dosage at 6, 11, and 16.

Some of the items you HAVE to have with tank mundo is Warmog's Armor Spirit Visige and Force of Nature for the hp regen and movement speed but other than those 3 itmes your build can vary on the enemy team or just on your personal preferance. Also i would recommend the Atma's Impaler so you wil have extra armor, and it gives you AD equal to 2% of your total health so you can do more damage.

With mundo i like to use Ghost and Ignite for chasing down people, running in and out of fights, and reducing their healing. But if you dont earn that much gold and the match has very hard enemies you can switch Ignite with Heal so you can take more damage, but you should always have Ghost unless you just never like having it then you can also use Exhast instead to lower their damage or slow them down so your team can get an extra kill.

With mundo if you are laning with Ziggs Talon Riven Wukong Brand LeBlanc and some of the champions that have high damage early game are people you should try to be careful around, because mundo isnt very good early game and also he is pretty squishy. The biggest thing you need to watch out for at anytime is a champion that has Ignite because they will reduce the effect of the healing mundo does and with that he is VERY easy to kill with no way to heal. Some of the champions that mundo is very good against are the squishy people such a: Teemo Sona [Soraka and Shaco because his cleaver will easily poke them down so they are forced to go back to base.

In team fights you usualy want to activate Heart Zapper first then throw Infected Bonesaw to slow whoever is trying to run away or kill your team. Then once you get in melee range you activate Masochisom for the extra AD. Once the enemy team starts focusing you pop you Maximum Dosage so you cant die, but if someone puts Ignite on you then you wont be healing as much and you will have a much higher chance of dying, so try to play as smart as possible when you have Ignite on you, it's best to save your ult until you have Ignite off of you so you can get a max heal but if your are forced to use it then you can because it is a very short CD.

Overall Mundo as a tank is extremly helpful in team fights with his slows, AoE, and insane HP regen. So i hope you guys enjoyed this guide, and found it useful, so go have fun throwing cleavers at people :)