Because of Senna's K/D/A and utility, she has a fairly average overall win rate. She does very well in the late game, with a winrate of 51.4% in that phase. Unfortunately, she does poorest in the early game, where Senna's win rate is 49%., The difference between her best and worst game phases is only 2.4%. This small difference shows us that her relative power is flat during the match.
Senna has been used a lot in the latest ranked LoL rounds. In the current meta, her popularity is 12.9%. A lot of players see her as a threat. She has been banned in roughly 10.2% of LoL rounds.
You will see her typically used in the support position. However, that is not the best position for her. The highest win rate position for Senna is bottom (53,7%). Currently, Senna's meta game is focused on dealing damage. In particular, her gameplay should primarily be focused on physical damage. Additionally, she is a decent magical damage dealer champion. Tanking is the least critical part of Senna’s build.
You should expect to have to to spend a decent amount of time practicing and learning to pick up Senna. Most League players believe she is an average difficulty champ to master. Senna mostly does physical damage (96% of her total damage). She doesn't deal a lot of other damage types and should not be played as hybrid damage dealer..
Senna deals a good amount of damage over the course of a normal round (17.441 damage). You may want to focus on developing her as a damage dealing champ to defeat your enemies.
If you are looking for a dominating damage dealer, then you should maybe consider this champ. She has one of the top kill rates in League amongst other champs. Moreover, she has a somewhat above average death total with an average of 6.4 deaths per LoL round. Furthermore, Senna has a high KDA ratio (2.6) with 12.2 assists.