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I feel like you understood most of what I was going for, but I probably wasn't clear enough: Yes, if mid, top, jungler or adc (or even things like brand support) on the enemy team is fed, you have to play around that. If it's a assassin, then that means better warding, trying to peel him off or pick him off in a 1v5, but the problem is that those actions aren't always possible (if your team lacks hard cc, if the enemy is grouping...) And also, I was going for the items, not the actions. If you play an AP champ, and see the fed assassin/snowball champ, you can build a zhonya and try to outplay him even by yourself, and that's why I love the idea of Zhonya's active. Even low mobility champions can now build a protobelt to have dashes to juke and outplay with, if they need it. The problem for me is that there aren't enough items that allow the adc to have that feeling. I'm not saying that we should remove the fact that an adc needs good positioning to not die, but even ap mages or assassin can screw up their positioning and have a "oh god, i screwed up" button, like say twisted fate often buys a zhonya's so he can make use of his ult and possibly survive if he missed the mark, but the adc who makes a slight misstep (and not nearly as big a misstep as teleporting into a 5 man cluster) will die, or get a GA pop. The GA, although it sounds like a good answer, doesn't really fit with what I'm saying here: You don't decide when it pops, and as such it cannot be used for an outplay. Everything about the GA is predictable, and as such, it isn't a tool that you play with, but another constant that you and your opponent have to play around. You gain magic resist and armour. If you die, you WILL revive in 4 seconds, with either 700 or 30% hp. If you are about to get bursted down, unless you can manage to dodge it through some other way, you will die. It's far different from the zhonya's which, although it does give flat stats, if you die, it might be because you failed to use it properly, or at all. If you're about to get bursted with a zhonya's on hand, it's your skills that will make use of the item. I am targeting the Zhonya's as I feel it's the only item that doesn't have an AD counterpart. I like its unique feel, and would not want to see a copy of it for adc's, with AD instead of AP as stats (that would make me sad as it would remove the unique feeling of zhonya's), but I would like to see something to replace it, a tool to dodge maybe, as adc's don't really want to stop moving or attacking, kind of like the Mirage blade from black market brawler game mode. I'm not saying we need THAT item, but since most people had the chance to see it in action, and that it added a lot more play potential, I think it speaks for itself and proves my point.

I do like the point you are adding about the "translate that pressure to side lanes". To be blunt, I approve what you said.The snowballing champion that roams to say bot lane as we are talking about adc could get a double kill, and get even more fed, and then I'd be happy to take the loss. The snowballing champion would then have outplayed me, my support, possibly my jungler and, of course, the mid laner. If we did our job correctly, the whole bot lane would have noticed the mid was missing, and warded. The snowballing champ would have found a deserted lane, lost time and gold and exp roaming, allowing our mid to catch up. There's a lot of risk and reward in roaming. It feels similar to the teamfight situation, where you just get murdered through your team, but here you can run away, while leaving your whole team to fight on their own because a fed enemy is zoning you isn't possible in a teamfight (and most likely will result in a loss). I'm fine with that however, as in lane phase you don't have your items yet, and need some other way to counter the roaming. Leaving is a good one. In teamfights, you can't leave as the team needs your damage, and yet you cannot get too close to the fed enemy. It is a problem that you can solve with perfect positioning, but as such things don't exist, and that even your full build doesn't give you a true outplay potential, I think there just needs to be an item allowing the adc to ouplay in teamfights.

TL;DR : Yes, you need to play around the assassin, but if ap characters have an item the allows them to outplay an assassin, why don't ad's have something similar?

a fed vi or olaf is the worst lol

or a full ap malphite that decides to press r and delete the adc