Dr mundo Guide

Tips for Playing Against Dr mundo

-Cleaver has a bit of a higher range, so you might be best to play inside minions, and take any grasps or Qs you can get but not put yourself in harms way when his cleaver is up.
-You probably won't kill Mundo alone unless his ult is down or you're able to spit him deep into tower (or you're way ahead). Probably best to play for ganks or for first item spike.
-If you use Q stun on Mundo while his passive is up, it'll still slow him. This means you can also probably step on his passive circle, or hit a W on him while he's slowed.
-If you have W up, you could just W out as soon as he ults, and then play for farm, or perhaps recall and teleport.

Oblivion Orb

I think this works well vs his ult, but I don't think I'd build it from behind. I would only build it if you have kill pressure with it.
Bami's Cinder

I think you can honestly just go heartsteel here, but I don't think it'd be bad to consider a Bami's item, especially in high elo. Hollow or Sunfire, depending on which resistance you need more (I do think Hollow passive tends to be worth way more though.)
Redemption

I usually consider this item against tanks, but I'm putting it here to make the exception. I think it's harder to eat Mundo because of his passive, and even if you do spit him into redemption you may not be able to finish him due to his ult.