Intro:
I generally play Dr. Mundo as a solo top laner, but you can also put him mid or bot lanes due to how flexible he can be. This build takes a long time to get used to, and to get built up, but in the end, you will be a Super Tank



Pros:
-Lots of HP and HP Regen
-Can tank just about the entire enemy team
-Super Tank



Cons:
-Very long to build
-Not that much damage output.
- Ignite, Executioner's Calling, Katarina, Varus, and Miss Fortune all have a 50% Healing and HP Regen debuff which severely cripples your Goes Where He Pleases (Passive) and Maximum Dosage (R) (Ultimate)

Tier 1:
We pick up Resistance and Hardiness because you are a tank. The more damage you can shrug off, the better



Tier 2:
We pick up Durability because as Dr. Mundo, the more HP you have, the more effective your Goes Where He Pleases (Passive) is. And we pick up Vigor to give us even more HP Regen



Tier 3:
We pick up Indomitable and Evasion to shrug off more damage. Two damage and three percent isn't much, but in the long run, it just might save your life. We also pick up Veteran's Scars to give us more HP. Remember, as Dr. Mundo, with more HP comes more HP Regen due to his Goes Where He Pleases (Passive)



Tier 4:
Now Siege Commander is an awesome Mastery! When you are tanking those tower hits for your team, you might need to take the tower down just a little bit quicker than normal, and this mastery will let you do it. While you are around an enemy tower, it's Armor is reduced by 10! That's about 1% extra damage! It's not much, I know, but instead of doing 50 damage, you will now be doing 50.5 damage. Add 10 attacks into that without the mastery, and that's 500 damage. Add in the mastery, and that's 505 damage (This is all scaled down to show the math easily). Now add in all the minions and other champions attacking it too. See how quickly it can add up?

Enlightenment is quite an awesome Mastery. It gives you 0.45% Cooldown Reduction per level maxing out at 8.1% at level 18. This allows you to spam that Infected Bonesaw (Q) even more often!



Tier 5:
Honor Guard allows you to shrug off even more damage. Why wouldn't you grab it? Mercenary gives you extra gold per champion kill OR assist. This mastery is probably one of the most overlooked masteries in the game. Why wouldn't you grab it? It allows you to decrease the time it takes to get all of your items



Tier 6:
Juggernaut is an amazing Mastery on Dr. Mundo. It gives you 3% increased HP, which in turn, because of your Goes Where He Pleases (Passive), increases your HP Regen. It also shortens the duration of disables by 10%. Combined with the Mercury's Treads and Heart Zapper (W) brings the Crowd Control Reduction up to 80%, but only if it's a stun or slow! Otherwise, it's 45%, sadly, but 45% is still awesome!

Greater Mark of Magic Penetration:
These are odd runes for a tank. I grab these runes for 3 reasons.
1) Infected Bonesaw (Q)
2) Heart Zapper (W)
3) Madred's Bloodrazor
All three of them deal Magic damage, therefore, they need the Magic Penetration



Greater Seal of Armor:
This should be obvious. You're a tank. You need Armor. If you don't have Armor, then how are you supposed to tank those pesky Carries?



Greater Glyph of Magic Resist:
This should be obvious as well. You're a tank. You need Magic Resist. If you don't get Magic Resist, how are you supposed to tank those pesky Magic DPS's (Ex. Malzahar)?



Greater Quintessence of Health:
Tanks need HP and as Dr. Mundo, with more HP, comes more HP Regen due to his Goes Where He Pleases (Passive)

My Spells:

Flash:
If you don't understand why we grab Flash, you shouldn't be on this page at all. If you ever watch the pros play, almost all of them grab Flash for a reason. It's great in multiple situations. If you are getting chased, you can Flash over a wall to escape. Or if you are chasing and they Flash over the wall, you can Flash over it to chase them down. See why this skill is a must?



Teleport:
Now, I generally pick up Teleport as my next spell, simply for getting back into lane quickly after leaving the lane to gank, protect another lane, or to buy an item. For late game uses, when there is a fairly big minion push in one lane, and Teleport isn't on Cooldown, you can go into a bush, and then teleport to that lane so that you can thin out that push. Overall, a great Counter-push/Ganking tool.



Other Spells I Would Use:

Exhaust:
Exhaust applies a 70% Attack Damage and a 35% Magic Damage reduction as well as Move Speed Reduction. Great for getting those kills. It can also be used to run away, while slowing and decreasing their damage. Overall, a great spell.

Ignite:
This Summoner Spell applies a 50% Healing and HP Regen Reduction on the target, and it deals damage, true damage mind you, equal to 25 x your champion level + 125. Early game, I would only use this if you know you are going to get the kill or you could also use it to stop their Health Potions from healing them at all. The pots get reduced to 50% healing over 10 seconds, and their passive HP Regen is cut by 50%, and then on top of that, they take true damage as well. Not too shabby, eh?

Goes Where He Pleases (Passive):
This is probably one of the best passive abilities in the game. Goes Where He Pleases (Passive) allows you to regenerate 0.3% of your max HP every second! The more HP you have, the more effective this becomes! Awesome, right?


Infected Bonesaw (Q):
Now if you ask why we max Infected Bonesaw (Q) first, you need to leave this page and go uninstall the game. It deals a percentage of their current health, with flat minimum damage. It also slows the target by 40%! NOTE: Do not use unless you know you are going to hit an enemy champion or minion! The reason behind this is that when the Infected Bonesaw hits an enemy, it refunds 50% of the HP, used as the cost of the spell, back to Dr. Mundo. It uses up too much HP early game and you don't have a high enough HP Regen yet! Once you hit level 6, spam Infected Bonesaw (Q) all you want.



Heart Zapper (W):
Now you may ask why we don't even touch Heart Zapper (W) until level 8. Well, for one reason. When you are a fairly low level, do you want your HP to be drained faster than you can regenerate it for the cost of 15%~35% Crowd Control Reduction? No, you don't. If you said yes, once again, leave this page and go uninstall the game. Once you get the Force of Nature, you can leave Heart Zapper (W) turned on all the time



Blunt Force Trauma (E):
Finally we come to Blunt Force Trauma (E). We need to get this maxed before Heart Zapper (W) because it grants you a base bonus Attack Damage increase, and then also grants you more Attack Damage based on the percentage of your missing HP. Very powerful early game!



Maximum Dosage (R) (Ultimate):
When it comes to Maximum Dosage (R) (Ultimate), if you don't pick it up at levels 6, 11, and 16, leave this page and go uninstall the game. Maximum Dosage (R) (Ultimate) Allows Dr. Mundo to regenerate 40% / 60% / 70% of his maximum HP over 12 seconds. So that's the equivalent of regenerating 3.33% / 4.17% / 5% of his maximum HP every second. Oh, and don't forget the include the 15% increase from the Spirit Visage that you have bringing it up to regenerating 3.83% / 4.8% / 5.75% of his max HP every second! Awesome, right? Just remember to try not to get caught by the Healing and HP Regen reductions by Ignite, Executioner's Calling, Katarina, Varus, and Miss Fortune. They all have a 50% Healing and HP Regen debuff that will severely cripple the use of Maximum Dosage (R) (Ultimate)

Core Items:
First off, we grab the Regrowth Pendant first so that we may stay in lane longer. Remember, as Dr. Mundo, you don't use mana, you use your own HP for your skills. We grab the Regrowth Pendant so that we have increased HP Regen. Now I have gotten into arguments with people asking 'Why not the Ruby Crystal? It gives you more HP AND some HP Regen due to Dr. Mundo's Passive Ability!' Now think about it. In lane, what would you rather have? High amount of HP Regen, or only 180 extra HP, that can be taken out quickly and only regain some of it? HP Regen, right? That's what I thought. Then you go and rush a Warmog's Armor. After you get this, most likely, it is out of the laning phase. Let your teammates get some kills as well. It doesn't matter if you get it or not, the Warmog's Armor gives you the same bonus HP and HP Regen whether you get the kill or assist.



Now you get the Mercury's Treads, for the Magic Resist and Crowd Control Reduction. Remember, you are a tank! You need the Crowd Control Reduction and Magic Resist!



The Spirit Visage is a MUST MUST MUST MUST MUST have item for Dr. Mundo. It makes your passive increase in effectiveness. It makes your Maximum Dosage (R) (Ultimate) increase in effectiveness. It makes your Force of Nature (which you don't have yet, but will get as the next item) increase in effectiveness. It makes your Warmog's Armor HP Regen property increase in effectiveness. It also makes your Cooldown time on all your skills decrease by a percentage! OH OH OH!!! PENTA-COMBO!!! HELL YES!!!



Now it is time for the Force of Nature. It makes you regenerate 0.35% of max HP every second! It also gives you a nice Magic Resist and Movespeed bonus which it very, VERY, nice! Why wouldn't you want to grab this?



So, now that you look back at the items, you notice you don't have any Armor. Well, it's time to fix that little problem. Start your Thornmail by grabbing a Chain Vest followed by a Cloth Armor. It gives a very beefy 100 Armor, and then 30% of all, yes I said all, physical damage is returned as magic damage to the attacker! SCORE!



Situational Items:
Now if you are wondering why to grab the Madred's Bloodrazor instead of something like the Guardian Angel, think about it this way. What is your only real heavy hitting damage output? Auto attack? You're wrong. Heart Zapper (W)? Blunt Force Trauma (E)? Wrong again times two! Your real damage output at this time is your Infected Bonesaw (Q). By picking up the Madred's Bloodrazor, it makes your auto attacks deal 4% of their max HP as magic damage! SCORE! Two major damage outputs is ALWAYS better than one.



If you would rather have even more Armor and Magic Resist, I would go with the Guardian Angel. It gives you Armor, and Magic Resist, while also resurrecting you every 5 minutes with approximately 1000 HP and 500 Mana (except the mana part doesn't matter to champions that don't use mana like Dr. Mundo). Not too shabby, eh?



Note:
Beware of people getting an Executioner's Calling. It reduces HP Regen and Healing by 50%