Can we get some kind of true damage reduction please?

Maybe per 100 of armor or magic resist you get 5% true damage reduction? (Can be lowered on certain champions like malphite.) It most if not all situations this would max out at 30% or we could simply put a hard cape at 25%. This would help combat certain true damage burst champions whose main damage output is unblockable. (Less on darius though) I get the point of true damage at times, but I don't believe that a champions main source of damage should EVER be true damage. It should be a supplementary or additional damage source. To clarify; 50 armor and 50 mr = 0 reduction. 100 armor and 50 mr = 5% reduction. 100 armor and 100 mr = 10% reduction. 300 armor and 300 mr = 30% reduction. (or 25% if a cap is implemented.)

EDIT: This will NOT effect ignite.