Expert take
Senna is an excellent pick when you know how to play patiently without becoming passive. She rewards supports who can read the wave, respect fog angles, and turn every small advantage into extra range. She is not the champion to pick if you want to decide every fight through direct engage; she is the champion to pick if you want to gradually suffocate bot lane, cover the map with your R, and make objectives hard to contest. Her real value appears when you accept that surviving, stacking, and protecting at the right moment often matters more than winning one aggressive early trade.