Kalista is getting nerfed. There's no doubt in my mind, that for even one second, that Riot doesn't know that she's a broken powerhouse and half of her abilities need better tuning and perfecting. She is the result of another champion just awkwardly pushed out into the game as quick as humanly possible and shown as a broken mess.
She can infinitely stack her spears into you and deal infinite damage to you. Not even Vayne can do that, or Darius. Everybody that has a passive ability that applies stacks always has a limit to which the stacks can be capped, letting an ADC be able to infinitely stack them and avoid the inability to stack them through blinds or other forms of CC is beyond broken. She deserves every nerf that she gets.
For the most part, anyway. There are four champions that take most of a game to get high stacks, but compare that to Kalista, and if she's able to put a spear in you every seven seconds for two minutes, that's about 50 spears and 600-700 damage easily.
I just find it ridiculous that if you're a "decently" skilled player, you'll stomp any champion without even truly trying. But yeah, she's broken and CertaintyT has been known to overload his champion kit designs, "Zed, Yasuo, Thresh, Darius, Zyra" Etc.