As a 2 mil
I wouldn't bother. You can play her mid as an assassin similar to ahri and then roam around the map and gank like a jungler, but top lane you really don't want to play her as every matchup shits on her. Tanks imidiately outdamage and become harder to kill for her after the first time, and juggernauts can just all in her and win off of raw bulk and damage. Her best matchups are the ranged ones where she can farm safer then most tops and blow up squishies, but she's very gank prone due to people seeing elise top and shutting her down early on, her only strength period in the game.
I pick her in mid whenever I'm against squishy immobile champs (
) or when I'm against
(she hard counters zed, he literally can't ult her if she rappels it.). She can all in anybody mid level 3 with ignite with ease.
Bot lane there is a high diamond elise otp successfully player her in the ADC role as an AP assassin, but a lot of his KDAs are significantly low, KP is low, and even he says he feeds a lot and gets carried which doesn't sound too good.
Support is possible but her mana cost really gate her, as all she can really do is an all in with cocoon then rappel out after chunking half somebody's health, then rinse and repeat.
Just stick with her in the jungle, she's bearly even viable there.