Pros / Cons

Pros

• Adrenaline Rush, and Grasp of the Undying allows you to sustain better than most top laners as well as trade evenly with them.
• Infected Cleaver is a versatile tool for harass, farm, chase down, and disengage. It also has a very generous hit-box
• Burning Agony's DPS is incredibly underrated especially after you build a Sunfire Cape. Moreover the ability also grants tenacity while toggled on.
• Masochism's auto reset meshes incredibly well with Titanic Hyrda active and Grasp of the Undying. Late game hitting all at once makes you deal a whopping 18% of your max health as physical damage.
• Sadism gives Dr. Mundo access to massive health regen for 12 seconds, this allows you to soak up a lot more more damage than even other hyper tanks can. The movement speed for the duration also functions as a kiting/disengage/chase down tool with your Infected Cleavers

Cons

• Early game, you get punished very hard for missing cleavers.
• You tend to be more vulnerable pre-6
• New items like Mortal Reminder/Lord Dominik's Regards give AD champions access to applying grevious wounds outside of ignite.
• Despite being a hyper tank you have no innate engage mechanics
• You lack any form of hard CC, making it difficult to peel for your carries.
• If you pop Sadism too early, then you can easily lose a team fight.

Alternative Runes Setups

Marks

• 9x Greater Marks of Flat AD
• 9x Greater Marks of Armor

Seals

• 9x Greater Seals of Armor
• 9x Greater Seals of Scaling Armor
• 9x Greater Seals of Percent Health

Glyphs

• 9x Greater Glyphs of Magic Resist
• 9x Greater Glyphs of Scaling Cooldown Reduction
• 9x Greater Glyphs of Flat Cooldown Reduction

Quints

• 3z Greater Quints of AD
• 3x Greater Quints of Percent Health

Situational Items

• So the reason you would want to take Frozen Mallet over Sterak's Gage is because that of the 40% slow for 1.5s that it provides to your autos. Your Q slows by 40% for 2 seconds. With 10% CDR from Spirit Visage the CD of your Q is 3.5 seconds. Properly weaving you Q and autos with Frozen Heart means that your enemy will only have a .1 seconds time frame where they aren't slowed by 40% this can be massive in terms of chasing down fleeing targets or peeling for your carries.
• Randuin's Omen is a great item into AD heavy comps or comps centered around a hyper carry. First, the passive reduces their attack speed and critical strike damage. Second, the active helps you stick close to ADCs who lack disengage
• Building Locket of the Iron Solari is a job that can fall to either the top lane, jungler, or support and quite often top and jungle don't like to build it. However, since Dr. Mundo scales with health, Locket is a great item as it provides health, MR, health regen, CDR, an awesome aura, and a decent active.
• In my opinion, Ohmwrecker is a heavily underrated item given its applications. One of Dr. Mundo's weakest traits is that he lacks engage. Being super tanky helps you push past outer and inner turrets, but inhibitor turrets are a different deal altogether. Ohmwrecker's active compensates for a lack of engage by giving your team the ability to literally push past a turret or simply take it because the enemy team can no longer play around it.
• An alternative choice to getting an early Spectre's Cowl is an Abyssal Scepter as it actually allows more damage from your Q(magic damage) and W (Magic Damage with a 20% AP/s ratio) however I'd likely take this item only if your comp and the enemy comp are very magic damage centric
• So the Rylai's/Lyandry's or Rylandry's combo can be deadly on Dr. Mundo as it makes his W an AoE slow, gives it more damage via magic pen/180 AP, and increases the current %Health damage output on his Q. On top of that it provides a combined 700 health. The drawback to building those items is a lack of health regen for their price and your team might think you're trolling. I'd likely only build this combo if I get super ahead early or if I'm in normals and just want to have fun.

Team Work

Jungle

• Zac This is pretty much a 10/10 combo between these two.Zac will be all the engage you need to run in and start keeping them slowed.
• Wukong I'd rate this combo as an 8/10 as Wu's engage can be slightly telegraphed and after he ults he's not as useful in a fight
• I'd give Gragas and Hecarim both 7/10 ratings. Both because they are not innately tanks. They are both good at blowing one person up, but they don't have the survivability of either Wu's Invisibility and Passive resistances or Zac's Hyper Tankiness and Passive
  

Supports

• Thesh and Leona both garner a 10/10 just off of their engage potential. Thresh might blow up faster than the tankier Leona, but the AoE from his Box can lock a lot of people down. Leona on the other hand, is innately more tanky from her combo and her passive allows for more damage to be done faster.
• Braum gets an 8/10 because while he is tanky and can negate a lot of damage/skillshots, his engage is highly dependent on either the other team being out of position, of he needs to burn flash to get a good ult off
• Blitzcrank deserves a solid 6/10 because all his engage potential is on one target. Moreover, its possible that he pulls the wrong target and ruins the fight for your team