For mid I use nothing but AP and MR runes, 21/0/9 for max AP and mana/mp5. I start 2 Faerie Charms and a ward. That let's you Q the crap out of people all day long and not worry about ganks. Then I build chalice and boots. If things go well I build Liandry's and then Rylai's. If not, I finish Athene's and build a Kage's. Then I build whatever the team needs. Elise is pretty good as an off-tank, which is usually how I go if things don't go well in lane. Otherwise just max AP and burst people down.