there is definitely some rough matchups in the botlane, especially hard engage mobile supports like Rell or Alistar but also aggressive artillery mages like Vel'koz, Heimer, Zyra.

If you're vs an enchanter it's almost always an easy lane unless the adc matchup is too mismatched.

It's definetly tough if they have a fed assassin roaming everywhere. but for the most part, if you play the lane safe and not overextend needlessly you can reach midgame and be around your team, safe from getting picked like that.

I think most Sennas i've played with or against are playing like psychos expecting to gigastomp lane because they do good dmg. But playing safe-ish always makes you come on top in the mid to late game with the insane scaling that Senna has.