What would happen if we lowered every champion damage source by 10%

I feel like Riot should do things like this just to see what happens, unless they'd have to go into the code and -10% damage on everything. Then maybe not.

ADC's would be even more overshadowing of all of the roles in the game than previously:

ADC's have access to most AD optimization items, everybody dealing less damage to them means that lifesteal is more viable and they can live longer; as assassinating would be increasingly more difficult. Burst champions would become less viable whereas DPS meta would become more viable.

The lack of damage means that supports would be given an overall buff because they don't need damage, and have utility to back up the damage dealing ADC's.

EDIT

Math to help out:

Let's say that Syndra does a combo of about 3000 Damage worth of burst damage:

3000 = 100% X = 10

Cross multiply, get 100X divided by 30000 which is equal to 300 damage, this is 10% so check your answer by performing this step 9 more times or just multiply what you have by 9 which is 2700 + the original number of 300, that's to check the math. Syndra would have done 300 less damage with a combo CDR BUT

Lulu shielded and ulted ADC so that's -1000 damage and Lulu also bought so those numbers are buffed more, in addition to a heal so let's say that this number is a 1600 subtraction to Syndras full entire combo (this doesn't include keystones) but the adc also bought so let's calculate the remaining combo:

2700 - 1600 = 1100

1100 = 100% X = 12%

100X / 13200 = 132

This number needs to be applied to each and every ability to Syndras combo. I am NOT going to do this, but you can see that people who use CDR's are devestated by this change in comparison to an ADC who can auto attack repetitively with only minor setback.

{quoted}

Thoughts? For better or for worse?

As the main of a champion who has been gutted repeatedly by riot nerfs this season I can honestly say I'd rather not have my main nerfed again. He does little to no damage early as it is, gets to 3 items and starts doing SOME damage, but is always just a walking ult because riot would rather issue crippling nerfs then fix the problem. I won't mention the champion I play, but there aren't many that won't guess/know who I play by that description.