Malphite's passive plus randuin's omen
So with full build malphite plus his passive, I managed to get my armor to 91%. But I also got randuin's omen passive, which is -20% damage from critical strikes. So if you're against a yasuo with 100% crit, and no armor penetration, does that mean he does 0 damage to you? o.O
Because your armor would be like 91% + 20%= 111% right, since it's multiplicative?