Probably an unpopular oppinion, but Mundo needs AD scaling.
Right now the only stats Mundo scales with are a paltry 10% AP ratio on W and a percent of his own max health on E. Other than that he only scales with CDR, levels, and attack speed/crit from his E's persistant bonus AD
Mundo has a sort of unique role but not really because 
does the "running targets down with axes as an unstoppable juggernaut" thing better, but a sort of unique role as a juggernaut that doesn't need to build damage items to do damage. Okay well besides 
and 
also being able to due to seperate stacking mechanics.
So he has a sort of unique role as a juggernaut that doesn't need to build damage and who mostly just exists to soak the enemy's onslaught while taxing them 1100g for a grievous wounds upgrade.
Now I don't mean to say him building and using tank items better than just about every actual tank is necessarily bad, but that it would be more rewarding if there was more direct scaling in his kit for other options.
Specifically:
Increasing the minimum flat damage portion of his Q by bonus AD. It would still chunk for 30ish% then 21sh% then 15ish% health, but would also give the ability more closing power as well as increasing its farming utility. Potentially changing the damage type to physical to better reflect this AD and proc 
could be interesting as well.
Add a 10% bonus AD ratio to his W on top of the 10% AP ratio. It isn't much, but this ability constantly being active contributes to a lot of potential damage over time in conjunction with the AD/Health item suite
Instead of a flat 60/70/80/90/100 (x 1+ (%missing health)) AD, have E give bonus AD equal to a percent of his total AD, with an additional flat amount equal to his % missing health on top. So something like 50/60/70/80/90% total AD + 0-100 based on missing health. Without building any AD this nets in lower extra AD early but more later, and more in general at low health (60-120 -> 30.5-130 at level 1; 100-200 -> 108.7-208.7 at level 18).
The results should be fairly net neutral for the normal full meatshield mundo, while opening up more room for his kit in lieu of not getting a complete rework
"yOu cAN't rUN fRoM MuNdO"
