Senna is an ADC, they released her under the guise of "she's a support with some ADC potential" which is bullshit. She's 100% ADC. Just because she has an ability that helps someone else doesn't make her very real ADC kit any less of an ADC kit. Just like pyke is very much so an assassin, just because they said he can be used as a support doesn't make him any less of an assassin. If you want to check her damage type go to your champions screen in the client and click on her, there's a little bar that shows an axe and a fireball, they have the gauge about 75% into the axe side, so she's an AD prime champ.