lissandra questions

So I've seen people play her top but isn't she a mage? My main question is whats the best lane to play her in? Ive seen alot of older posts saying that shes not good mid (top or support is what I have seen people calling her). I'm relatively new to the game and have played her a couple of games mid with mixed results. I played a game vs zed before I really understood her mechanics and got squashed but the second game I destroyed a malzahar. Idk if it was just because that malzahar didnt know what he was doing or what. And the final question is she viable to play in the current season shes pretty fun to play as and I'm considering buying her but I'd like to know more before I do.