Well she is one of the most mobile mages in the game. Imagine someone with brand or Annies click abilities and such high mobility!?!?!? That would be insane!!!!!
If you think she is underpowered. You're wrong my friend. She is one of the best mids right now AND has been since release. Her outplay/snowball potential is insane. It just takes more skill then some champs. Her kit is based around you landing a good charm and a double Q inlane. While in team fights her ablitiy to get in and out while nuking the carry. Is insane. Her AP scaling is fine. Have you seen the nukes she does with a ludans echo with a double Q? Half health on most mids easy. Don't even get me started on when Death fire was still in the game.....oh god.
She is perfectly fine. If anything she is a bit OP and I would not be surprised if she got a minor nerd (I pray to the league gods she does not)