Percent damage reduction should not stack
Just played against a Graves that built this: 
(With a 
to top it off). All of those items stacked together add up to forty percent damage reduction and it's total bullshit. You can't even build armor/magic penetration against it. Champions who build that shit are basically packing an 
on demand in a 1v1.
I honestly think that Graves' problem wasn't that he was too tanky on his own, it was just his synergy with this build. Shacos that built the / combo pre-rework were just as frustrating.
for example is a good desinged item as you can clearly see the Shield that reduces your Armor.
