#1 - April 11, 2018, 7:46 p.m.
A lesser known change is how armor interacts with Block. Currently on alpha, the amount of damage you block reduces as you get more armor. For example, on my 117 Paladin in Alpha quest gear, I have 33% baseline block DR. When I hit SOTR, it drops to 14% DR.
Now if you consider Holy Shield, a Protection Paladin talent, I gain the ability to roll a block on magic attacks. This has been a tool since WOD for Paladins to counter consistent magic bosses like Krosus. With the changes to SOTR, Holy Shield will be the only way to reduce magic damage for Protection Paladins in BFA.
However, when you put both changes together, pressing SOTR reduces the amount of magic damage I could reduce via Holy Shield. In a fight like Krosus, it would be better to spec Seraphim and sit on SOTR charges (or use macros to cancel the aura) than spend them and take more damage.
This is problematic and counter-intuitive. Pressing an active mitigation button shouldn't cause me to take more damage than I would have if I didn't press that button. No other tank has to deal with an interaction like this. It will lead to /cancelaura macros where am I pressing SOTR for damage then canceling it right away to maximize the damage reduction from Holy Shield. Imagine having to do Krosus but having to /cancelaura SOTR constantly as to not take more damage than we should be and maximizing damage/threat.
There will be points during Mythic bosses where, I'll be thinking, "Here comes the magic hit, let me click off my SOTR so I can increase my damage reduction vs Magic." Tanking shouldn't work that way.
/cancelaura macros for Active Mitigation Buffs against spell damage is not good gameplay and changes should made to avoid this situation.