Tank rengar?

Greaaat its happening again tank akali tank fizz tank ekko tank ekko and now tank rengo....he built nothing that game but titantic and warrior in terms of offence had around 4000 hp and could one shot our adc. Literally kill her in under 2 seconds just like every other assassin but he also brought stormraiders so he could just get right out after because hes immune to cc with a 40% speed buff sigh...Riot when will you ever learn to balance assassins so they can't go tank? :\