Aatrox Buff Idea

I've been playing Aatrox and have been mulling it over for quite some time. I believe that when Aatrox becomes hellbent, the passive Aatrox receive for casting spells and being longer in a fight, he should receive a 10% damage reduction received from all sources. This would apply as he's fighting and after he resurrects. This would make it so he wouldn't pop like a balloon due to the items he has to build to be relevant. It's also fitting his lore because Aatrox becomes empowered by battle.