Alright, totally redid my mundo build because I decided mundo isn't a real massive tank like some people see him as. He also isn't a massive dps, and I hope for God's good sake he is not a heavenly caster that I never knew about... But I found that Mundo does real well with A) lots of hp, B) good survivability items that are high hp that ad to his regen hardcore. Who more regen when ignite pwns it? Well ignite does cut it in half, but if you get your warmogs, spiritPs, FoN, omen... Your getting so much hp that people ignite you thinking your ulting, then find out your not and someone else ignite's you when you actually are ulting, and you still get 1.5-2k hp from it when it finishes :D.

Your job, run into a fight, cleaver the heck out of the carries, use your merc treads + burning aggony (btw burning aggony is very under used, why 30% reduction to all CC eh? Along with my merc treads!? Your stuns are like .2 seconds long! BWAHAHA *mundo skips into the distance, turns around a tree and comes back nearly full hp* Bwahaha! CLEAVER! So, pop burning aggony, run through the team and cleaver those fleeing ad carries and let your team take apart the confused team because a mundo just ran right through their CC and stuns while trying to save their poor ad carry.

I go hp/lvl yellow runes, flat hp quints, armour pen red (because you sometimes machoism at low hp and whatnot), and CDR blues (because your ult comes back that much faster... why not?!)

You could throw on a sunfire cape justto give you more beefy+armour+annoyance fetures, but I think stacking warmogs can be much fun, force the ad carry to get bloodrazer which doesn't work that well with merc treads/spiritPs/FoN anyways. If you want then trade out omen (</3 beautiful active slow but I understand if your not one item activator type of person) for sunfire or something beefyer, and grab banshies veil or an impaler and be the "I am Mundo tank! That Do Massive damage because I so fat! Mwahaha!"

So good luck, build high hp, get resistances so those high armours and mercs so you can get away and stay the heck away from ashe, because she is your bane of excistance. Perma slow, we mundo's say mundo goes where he likes but with constant ice slowing over our limbs even our 60-70% CC reduction doesn't help!!