I have Flamel awakened. Totally worth it!

I don't treat her as a tank though. She's a soldier who packs a punch and a healer primarily. Park her behind a tank and she picks off extras well and heals the tank. If anything I treat her as tank #3. Also on maps where there are big open spaces and/or few ranged slots she is a god send! Flamel is one of those units who opens up entirely new strategic avenues.

Also worth taking into account we have no idea when these events will come and in what order. Its pure speculation so build to what will help you now. Generally the gacha units are better than event ones anyway. You could wait for Serra but you have Flamel now. If your Healer stocks in general aren't great she helps a lot.