I think it would be great for the game if the wombo combos were reigned in. What if damage multipliers maxed at +50%. So, no more double stack deep wounds then bullseye. If you get Same goes for defenses...max damage reduction of 50%, before defense. So no stacking scale armor and resist physical on a collosal champ and it being unkillable. Full immunity in most cases should be turned into resist 3. With the few special runes having 'eater' versions.
How would i do that? I'm not a programmer but i assume that is doable...if they can limit other effects from stacking, they can do it for damage reduction. So say you have resist physical 2, and scale armor. That would add up to 60% against physical, so would cap at -50%. Actually I'm not sure if defense is calculated before or after, but mechanically speaking it should apply first. Basically it just brings in the boundaries so there arent so many OP ability combinations.