Long-Term fix for Assassins and Lethality (both AD and AP)
I understand what Riot was doing when they made Lethality a thing, they where attempting to make a core stat for Assassins that would prevent tank Assassins from being a thing (insert 
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). Unfortunately, balancing anything AD in this game is akin to balancing cards on top of each other to make a house; you fix one thing only to have the rest fall apart. This to me, says that AD is flawed itself, but I'm not going to air my grievances about it here; I'm going to focus on making Lethality as good stat that is built for Assassins, but not abused by everyone else.
At its core Lethality is a good idea, an Assassin-centric stat that focus on the strong point of the game for Assassins: early game, but in execution is too strong for any AD-based champion. This coupled with the fact that AD Assassins have the issue of_ always_ doing massive damage, means that Lethality has become a cancerous mess of a stat that has warped the entire meta of the game around it.
What I propose is both simple but fairly involved: Lethality would now grant a 1% per point bonus damage as true damage, based on off abilities and basic attacks, whenever you strike a target made _VULNERABLE_ by certain champion mechanics you triggered by your champion. With 60 Lethality and 200 AD you'd see a champion deal an additional 120 true damage if the target is _VULNERABLE_.
To make a target _VULNERABLE_ require you to hit an enemy with certain abilities, and only Assassins could make a target _VULNERABLE_, making it useless for non-Assassins. For example:
 applies her Q to her target, making them _VULNERABLE_ for 3 seconds, the target takes greatly increased damage during that 3 second window, but afterward they revert to normal.
_With  mentioned, I would like to say that with the proposed changes, their would be an introduction of AP-centric Lethality items added to allow for AP Assassins to leverage the mechanic as well. Because of AP scaling, they would have lower max Lethality levels, but the damage would definitely still be there.
_
Its important that the _VULNERABLE_ window remains fairly short, with 3 seconds being about as long as it should get. Some champions might also have multiple ways to make a target _VULNERABLE_. For example:
 can make a target vulnerable for 1 second if he hit them with an attack from his Living Shadow OR he can apply it from his Ultimate, Death Mark for 3 seconds.
**Another example of this:**
 can make his target _VULNERABLE_ whenever he applies his E successfully to the target for 1.75 seconds, from attacking a target with his Ultimate active for 3 seconds.
Its important to note that ONLY Assassins would have this ability and the _VULNERABLE_ would be unique for each Assassin. With this in mind, the baseline damage of Assassins (mostly the AD Assassins) would take a slight nerf to the point where they should do damage as though they're a fighter like  or ; the damage is there but you won't get wrecked by it in 2 seconds flat. Only when the _VULNERABLE_ damage window is active would these champions have their damage catapulted to deletion levels of damage.
Thoughts? Comments?
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ALL SAY HI! The only difference between mages and Assassins is that Assassins fight with pointy things, mages casts spell of death and destruction.
can make his target VULNERABLE whenever he applies his E successfully to the target for 1.75 seconds, from attacking a target with his Ultimate active for 3 seconds.
This is too situational and his ult already rewards him with bonus ferocity , this will just make him feast or famine