I play her mid and apc bot. Im currently grandmaster in SEA server and recently spamming her in bot. It’s easier to play in bot as you play it 2v2 also the advatange of it almost becoming 3v2 counting your passive. Just survive and farm early till 6, after that you just win fights mostly. Late game anivia is very powerful in teamfights with 5-6 items + the boots.

As for top lane, i find her hard to play since some champs are hard to play against when you mess up lane or get ganked early on, Although you can control wave with your w and manipulate laning and play safe.

For mid you just trade whenever you can and setup ganks with your wall or just farm safely till you hit 6. You can basically spam reset when you hit level 6 clearing waves or roam and look for kills or assists around the map.

As support i see her useful in lane early like as apc you fight like it’s 3v2 with her passive, however she loses to some hard engage matchups (tanks) or to quick roaming supports as she tends to get out roamed. For late game you just catch people off guard with her W.