500 attack damage ranged champion, it's fair i promise
Now that i have your attention let me paint this picture. ADC's can no longer critically strike, but in exchange they average between 500-750 Attack Damage, with ability ratios scaled to account for the new numbers (can't have someone firing a line nuke and clearing the whole wave just off that). They loss none of their attack speed, and their kits still function the same as they currently do.
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only giving 25% crit would be a huge blow to how effective that combo is. Hell i can almost stand the idea of 4 items giving 50% crit, high chance to do it each attack BUT equal chance you will not get it.