Increase Marksman diversity by lowering the emphasis on auto attacks.
One of the long running problems with Marksmen is that by end game most of them turn into "click and win", especially if they got snowballed into hyper carry status and manage to get 40%+ crit.
Rather than focus on the "crit to win" aspects, wouldn't it be healthier to focus on their abilities instead? Because once they get BT, IE, and PD most of them become nothing more than right clickers as using non-AA abilities actually has the potential to LOWER their DPS.
Well designed (in my opinion) Marksmen.
Tristana: A siege expert who blows up towers one after the other. Her gameplay revolves around the Explosive Charge ability.
Vayne: Her short range, CC w/terrain, and bursts of invisibility makes her into a powerful hit an run assassin who loves the dark/cramped confines of the jungle. She's great at hunting down isolated targets thanks to her "Silver Bolts" and "Night Hunter" passives.
Kog'Maw: Long range HP% autoattacks allow him to melt through the normally beefy front lines, and his abilities are great for poking down people clustered around a tower.
Lucian: Properly weaving his passive in between abilities gives him extreme mobility. His ult increases this even further by allowing him to both attack and chase after/evade his opponent at the same time.
Graves: Buckshot buckshot buckshot. Nothing more fun than jumping up into someone's face and then blasting it off with your Q. Creates dynamic decision by making you choose between safety and damage.
Twitch: A sneaky little rat that rewards people who are good at building up his Deadly Venom.
Miss Fortune: Kit revolves around Impure Shots. Though I feel that perhaps "Make It Rain" should be rebalanced to apply/benefit from it as well. (Lower base with higher potential at max stacks)
Caitlyn: Rewards the player for staying in bushes and laying traps that leave her enemy helpless. I think "90 Caliber Net" might be a bit overkill in the safety department and could be replaced with a less "melee hate" ability.
Ashe: Revolves around Frost Shots and Ranger's Focus. Still a bit bland, but much better than she was pre-rework.
Draven: Focuses on keeping up his "Spinning Axe" stacks and catching them so he can re-activate "Bloodrush".
Kalista: Rend is a great mechanic and she has a very cohesive kit. Her only problem was how ridiculously hard her passive dashes spat on the face of slower melee characters. Since then she got a few nerfs that brought her in line.
Sivir: THE AoE champion. She has been through some tough times, and a rework, but her use of "Boomerang Blade", "Ricochet", and "On the Hunt" give her a very unique niche as a heavily team fight centered Marksmen.
Ezreal - I rather like the way his kit is very ability use heavy. To the point where AP Ezreal is a possible tactic. Even if the champion himself infuriates me to no end. D:<
Less well made:
Jinx: Her Q is focused on auto attacks, but does so in a way that rewards her for taking risks by making stacks fall off quickly. "Zap!" is also quite powerful. Though, like Jinx herself, the kit lacks somewhat cohesion as a whole.
Quinn: Her own self isn't that bad, but Valor is a bit lackluster. She lacks the survivability and sheer damage melee carries like Yi or AD Udyr have. They were going to buff Valor at one point by making it a low CD toggle, but nothing came of it.
Bad:
Varus: His passive is only good if you're strong enough to kill your opponents. He's supposed to revolve around detonating Blight packs, but lacks the ability to easily spread them with his low attack speed AND he lacks the ability to repeatedly activate them with his long CDs.
Corki: His kit is all over the place. Passive does True Damage just because. Q+W are magic based AoE attacks. His E has potential to be interesting, but it's only helpful if you're winning. (Because he has to face away to run.) His R is undoubtedly his most unique skill.
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Also, you realize you just said that Kalista was well designed right? XD
and
(Best rework ever), I like abilities like explosive charge and blighted quiver that has you weaving abilities and autoattacks.
that doesn't mean they are the norm just more ability focused ones. ADCs are more than just "click and win" champs specially by late game in which if they position poorly that usually means game. ADCs shouldn't be changed to be more ability focus, that why AD casters exist