Swain and Nocturne
I know when people think of op champs they generally dont think of these but my friend has been playing swain for 1 week and hes gotten 5 pentas. I will admit before level 6 kinda weak but after you dont stand a chance, his ult and his scalings are ridiculous. Nocturne has EVERYTHING in his kit: Taunt, spell shield, dumb broken ult, and a q that speeds him up and has a ridiculous scaling. I've seen every possible thing and there is only ONE item that can counter a little which is zhonyas (same thing with rengar ult) so riot is basically forcing adc's to build zhonyas when there is a rengar or nocturne on the other team. You CANNOT whatsoever kite nocturne his spell shield will block any cc or snare or whatever you have, his taunt will let him rek you and you cant attack, and his q speeds him up to get to you and does a ton of dmg, not mentioning his ult cd and him reking anyone who doesnt have a zhonyas or isnt EXTREMELY TANKY.
sincerely, a person who is becoming sad with this game
Is a champion meant to latch on and not let go, you aren't supposed to be able to kite him, and only the best 
players and maybe critical strike 
players can kite him. And he does have a ton of sustained damage after you are feared and under the effect of duskbringer. His ult CD is VERY LONG early on, the first 3 items I build are 
(30% CDR) But unless you buy 3 
s before going on to those items you wont have a short CD before mid game, And Mid Game is 
but he does well) His ulti does not work on a group of enemies, Hes very single-target like 
, and he does not have great initiation by himself as his primary role is assassin and he will have to choose between The Immense Sustained Damage and Immense Survivability. 