what is your favorite uninteded item/mechanic usage?

So, what I mean by the question is hard to explain so ill give you an example. My favorite was black cleavers initial launch, when the passive was not unique. Once it was at max stacks it did 30% of your armor, so 5 of them gave you 150% armor pen, meaning that the more armor the enemy had, the more damage you did. Another example would be dodge, which is quite an old feature (only jax has it now), and jax could get something like 80% dodge chance PASSIVELY. I don't want glitches/bugs, so yorick and guardian angel doesn't count. i want something where the item/mechanic works AS INTENDED, but the final product effects were not thought out. Did you like relic shield working on anyone so double adc double relic shield lane? did you like the new double smite making almost anyone able to do drag at level 2? How about Warwick with skirmishers sabre top lane, stacking on hit effects, so his ult could insta kill anyone? Share your favorites/memorable ones