I was thinking, what if seperate base armor/mr stats and bonus armor/mr stats from eachother and let them be calculated on top of eachother?
Two new stats could be introduced: Studded & Cloaked:
* Studded will replace bonus armor. He reduces damage of physical damage spells after reduction of the base armor. So let's say if armor reduced physical damage by 30%. Studded will reduce the remaining 70% but only on abilities. It will no longer reduce damage from auto attacks!!
* Cloaked is similar but than for mr
Both Studded & Cloaked are capped on 25% reduction (so in the example 1/4 of the 70%, so he will have 52,5% of the damage left)
Base health & base health growth get's a massive buff. Giving tank more health to work with but with less armor to protect themself against auto attacks. This makes them still weak against bruisers & marksmen but stronger against mages that poke them out of lane. Overal they will still be in a serious disadvantage in range matchups.
With the new changes tanks should have relative low base armor/mr. This makes Studded & Cloaked a lot more viable on them since it will drasticly reduce more damage than other classes that start with higher base armor/mr.
In terms of peneration items. Juggernauts still have Black Cleaver that reduced their base armor. So building armor against someone that has cleaver will be rewarded. The same concept aplies for voidstaff that only penetrates the base mr.