[I]This is not a troll thread, im here to explain my point of view[/]
The big problems with leblanc
Le blanc has to ability to poof around and return to her original spot which in terms of mobility and harassment is probably the golden ability. To be able to jump around and toss her silencing balls then return to her original position is way too powerful. The player being attacked cannot even retaliate to le blanc because of the silence and how fast she can go back to her original position. Also, Le blanc's ultimate allows her to cast another of her spell which is even more powerful. Le blanc can easily just jump into someone harras till they are approximately 1/4 of their health. Thus Le blanc will jump directly at the opponent, rooting them, and silencing them. This is by far one of the most op combo you can do to a melee character. The opponent will most likely die before they get to land any of their abilities to save them. After get couple of kills early game as le blanc, she just becomes more devastating at the late game where she racks even more kills because she was fed early game.
And yes i know someone is going to say "Stack magic resist NOOOOOOOOOOB". Stacking mr is clearly not that easily said than done. If you are another caster/dp what are your options of mr items? banshee veil, Force of nature, ect. By getting these types of items makes the player fall behind compared to other caster/dp. Besides the items designed to be mr resistant and give the mage/dp the ability to still dish out damage does not give enough mr to become worthwhile. Even for tanks to stack mr, the more mr they get it gets less cost effective for the percentage they reduce.
I conclude Le blanc is, in my opinion and many other is OP.