Across 1,067 ranked games on patch 16.21 in Master and above, Kalista mains win 53.5% of their games in the bot lane.
Their most common build appears in 94.9% of those games and wins 53.0% of its 1,013 games.
It starts 
two Health Potions and 
Doran's Bow, completes 
Statikk Shiv, 
Guinsoo's Rageblade, 
Terminus and 
Jak'Sho, The Protean in that order, and takes 
Gluttonous Greaves.
In the bot lane, Kalista mains fare best against 
Zeri (won 68.0% of 25 games), 
Caitlyn (won 66.7% of 27 games) and 
Tristana (won 61.9% of 42 games).
Their hardest matchups, the champions that counter Kalista, are 
Jhin (won 43.6% of 55 games), 
Varus (won 40.0% of 25 games) and 
Xayah (won 43.3% of 30 games).