Certaintly T you designed Darius
after all you should know how melee feels against 
after all you should know how melee feels against 
As long as Kalista isn't ahead of Darius, I think Kalista is pretty easy for Darius to kill if he gets a pull on her.
His W attack speed/movement speed slow makes her pretty easy to stick to while you burst her.
You pull her, W instead of Q'ing first because she's going to AA and jump back, so you get your slow off, she jumps back, then you Q for the extra damage since she just jumped into the perfect damage range. Then press R for the kill 'cause Kali is squishy as heck.