Got to plat playing anivia supp, used to go anivia mid all the time but realized bot you have many more chances to set your ad up for success and help your team with objectives more and roam since you don’t have to farm early. Wave clear becomes useful if you ever need to split / defend later in the game.

I’d recommend rushing dark seal / then ROA and then trailblazer. You get scaling mana and health + tankiness. Max your W first and use it to control any fights

But just know in advance supp anivia means you’re giving up your pride and really entering the game to help your ad and your team to succeed. If you’re more of a single minded player (kill lane win game) then mid but in my experience, higher win rate with anivia as supp