Against sona, Most Sona’s will run through their mana incredibly quickly through poking and providing heals. Capitalize on this by looking to fight her when she has no mana available.

Sona is incredibly vulnerable in the early game. Before level 6, try to abuse her as much as possible. Once she is level 6, her kill pressure increases as her Ultimate R is a great duelling tool and has great gank set up too. 

The best time to play aggressively is when Sona overextends to get stacks on her Spellthief’s Edge. When she is overextended, try to play aggressive and burst her down when she’s positioned forward.  Against sona, Before level 6, try to abuse it as much as possible. Once it is level 6, its death pressure increases as its Ultimate R is an excellent duel tool and has a great gank set up as well. The best time to play aggressively is when Sona superextenses to get batteries on her Spellthief. When she's overextended, try to play aggressive and explode when she positions herself forward.