kassadin and cassiopeia suffer from the same issue
Both champions are actually really strong if played right but there main issue is that they are late game powerhouses and countered by there not so good laning phases(which is healthy for balance) normally the 2 champions won't ever reach there power spike/full late game power due to games ending sooner then they want to i have only seen late game kass twice(it is powerful)and late game cassiopeia like 2 or 3 times(which my god is broken when played by someone experienced) they just can't reach the stage where they are these annoying powerhouses in a lot of games
a few times and i gotta say he can be op but well played...which I'm not totally doing haha :)
I'm sorry ill just doge your poison
i have made you lesbian and unable to poison me for awhile
we all know this one
BALLS BALLS BALLS BALLLS basically has a teeeeeeeeeeny bit longer range then her E
also unless you can micro her poison(which i for 1 can't)her early isn't all that good without landing her slow poison skillshots