Blade of the Ruined King is a problematic item
I may be wrong because this may be just a coincidence, but have you realized that most champions that are arguably considered "broken" now are champions to which one of the core items is 
?
I am referring to champions like 
and most other Devourer junglers; they are not broken by themselves but Devourer made them too powerful. Many champions that used to be considered broken also have BotRK as one of their core items; examples include 
- Most of those champions were nerfed.
deserves a special mention because she is one of the most controversial champions as of now and her core item is Blade of the Ruined King. She already has a lot of tank busting and dueling potential without that item and this item just makes her unduelable.
This may just be a coincidence but don't you think that one of the reasons why those champions are powerful, maybe it's their synergy with this item? Seriously, Blade of the Ruined King was meant to be an anti-tank item but it is just too good in general. It offers consistent power that allows most champions to be better duelists. The enemy team does not have to have good tanks, as the current health passive works well regardless of how much health they have. The active also allows a champion to chase other champions better. A proof of that is Blade of the Ruined King being a core item to just about any champion based on on-hit effects.
One of the reasons why Devourer is considered broken is due to its synergy with Blade of the Ruined King, allowing a champion to do 16% of a champion's current health in damage with just one attack. This is very stupid, especially in the hands of champions like Master Yi and Shyvana, which already have abilities that allow them to double on-hit effecs, also they have pretty good on-hit effects of their own.
Maybe it's time for Riot to consider looking at this item? Nerfing it, or reworking it, or replacing item with another AD item that would be more balanced but would still allow for AD champions to deal with tanks.
