A nice idea, but that item sounds terrible. The counterplay to ADC(Marksmen) is to CC or gap close on them, tank their damage and burst them down.
So there's already tools to combat that, have your
up, build
, stay away from enemies that can jump on you. Being good at that while still doing damage is a big part of what makes you a good ADC, and it's important that skill expression isn't taken away by giving ADCs an exclusive extra get out of jail card.
If that kind of item was good, ADCs actually would be as unfair as a lot of people that hate the role like to pretend they were before midseason. The only way it would be balanced is if that item was intentionally trash.
The reason ADCs are bad right now isn't because of their natural counterplay. Their strengths have been gutted and spread across the other classes. Damage is everywhere, so you don't need an ADC to deal consistent DPS. Turrets have been made laughably easy to take by everyone, so you don't need an ADC for objectives. Their power spikes were pushed back, and snowball was increased to end the game early, so many ADCs can never expect to hit their power spikes in even lanes. Their base stats got nerfed, so they struggle to lane against other classes, even in the duo lane, which was the only lane with enough safety to keep them from being jumped on so they could play to their ranges.
If the other classes have damage and objective taking ability on top of their other strengths, spike earlier and don't need to worry about being outscaled, plus they can beat ADCs in every lane, why pick an ADC? That's what the actual problems are.
It would be nice to have some new items to allow for better build diversity and maintain the relevancy of the class without assassins and fighters abusing the items (
,
). But a second flash would not be that item.