Mundo is STILL too strong, and it's no suprise...
CURRENT HEALTH DAMAGE 15/18/21/23/25% ⇒ 15/17.5/20/22.5/25%
Shockingly, removing 0.5% of his cleaver's HP damage on a couple of levels didnt suddenly make him less obnoxious.
MAXIMUM DAMAGE TO MONSTERS 300/400/500/600/700 ⇒ 300/350/400/450/500
Reducing his cleaver damage to monsters at higher levels barely does anything to slow down his jungle clear. By the time that nerf actually starts to become significant, he already has levels in W as well as most likely a cinderhulk(Ive seen sated mundo too though, he can pretty much get away with anything right now), Clear isnt even a major factor..., he's still too strong in lane either way.
Why is he suddenly so strong? Check out the resolve mastery tree.
Recovery: 2 health regeneration per 5 seconds.
Runic Armor: 8% stronger shields and self healing.
Perseverance: Grants +50% base health regeneration, increased to +200% while below 25% health.
Swiftness: Grants 3 / 6 / 9 / 12 / 15% tenacity and slow resist.
And for Keystone, if he isnt much of a team player, Grasp of the Undying: Every 4 seconds, your attacks against an enemy champion deals 3% of your maximum health in magic damage and heals you for the same amount.
But, he also goes quite well with: Bond of Stone: Grants 3% reduced damage. While within a 1000-range of an allied champion this bonus is doubled to 6% and 6% of the damage they would take from enemy champions is dealt to you instead.
Of course, plenty of champs can get a lot out of these, but they synergize absolutely perfectly with Mundo's playstyle. He's a healing tank who's only resource costs are HP, and he starts the game with a mini spirit visage, has bonus tenacity to go with his W, more healing on attacks, and more% hp healing to go with his passive in the rare occasion that he gets low HP. Since Mundo tends to stack a ton of HP, these percentages really become significant.
Throw in the extra burst given by his "headbutt", plus the damage from "Grasp of the Undying"(which again, is quite a lot due to his health stacking) and you have something that does a f**kton of damage, is impossible to peel, and impossible to kill.
Seriously, try getting him off of your carries, he gets like 30% cc reduction from his W alone, and 35% move speed for 12 seconds on an ult that makes him litterally impossible to kill, and has a very low CD with even a moderate amount of CDR.
Edit: Also, I forgot to mention the nerfs to grievous wounds from 50% to 40% healing reduction. Yes
is back, and it's cheap, but with his core build, he can heal right through it without a problem, unless 3-4 people are pounding on him.
TLDR: New masteries, and the additional burst from his "headbutt"in additon to the grievous wounds nerfs pushed Mundo over the top, and the nerfs to him did nothing to address this. He's still too strong.
In my opinion, headbutt should simply be removed. If he is going to be completely unkillable, he does not need the extra burst.
