Could Karthus get rewarded for landing consecutive skittles?

I'd really love to see karthus get some tweaks in this area. In particular The change I'd like to see is that defile would do more damage to champions that have been hit by more lay wastes.

1st skittle landed- no change, enemy is marked as 'defiled' 2nd- enemy receives the slow debuff from wall of pain 3rd- enemy receives MR debuff from wall of pain 4th-nothing 5th- enemy takes 20% more damage from defile and requiem