Like for example x item gives you super fast attack speed but your crits do alot less damage. that is just an example and im sure these items would have VERY specific stats so they arnt used on certain champions and never picked up on others.
What I mean by that is for example an ADC who doesn't use a lot of crit in their build could just buy that with no trade off.
There used to be an item that had an active that gave you 200% attack speed and guaranteed crits for 3 strikes, but you lose the item's given attack speed(?) While it was on cool down.
So yes. It was underutilized and otherwise hyper niche, so it was scrapped.
Knight's vow is kind of like that, reduce damage for a teammate but take more yourself
So, you're suggesting items that have explicitly negative effects, instead of just the 'cost' of using up a slot that could be used for another item?
I don't know how much thought they've given to any items of that sort, but if they did, they'd have to be super careful to make sure it was actually a negative no matter who bought it, otherwise it'd quickly become a must-buy on the ones who didn't care about the trade off.
Mejais is probably the closest thing that exists since with a couple back to back deaths you can quickly have an almost useless item on your hands, but with the breadth of champs in the game it's hard to make risk-reward items that are balanced on everyone.
that's exactly how you get abuse cases.
champion that can use this items while the drawback doesn't effect them would be incredibly overpowered. For instance, any on-hit champion that doesn't crit would be broken from your example.
I really hope we'll get some of these one day. While it could be a problem on carry roles - Tanks and Supports (non-carry/snowball roles in general) could get amazing itemisation options unabuseable by other roles.
Something like: Restore 25% of incoming DMG -> DMG dealt by your abilities and autoattacks is reduced by 50%. 1000HP 40 Armor. 3000 Gold. A heavy lategame Item exclusively for tanks with synergie in Spirit and Thornmail, counterable by GW. Fair enough?
Honorable mention: 
technically, 
line already is one since the passive on hit effect disables if you kill a minion.
Sword of the Occult was one of these and so is Mejais.
In a way that is....
I think something like that could be nichely abused by the pros too hard.
Yolanter12/20/2016, 12:08:02 AMI am sure riot has thought of these items but items like that could easily have an item that counteracts those tradeoffs as well as runes and masteries that could counteract them. They just are not that viable. (Also what adc doesnt use crit in their build?)
