I recommend you to use Venti as support because that is rather easy to build than going for a damage build. That way, you'll have plenty of time to perform team rotation and switch to your main damage dealer to hit grouped enemies. Just use Venti's burst, take benefit from the elemental infusion and resistance shred. Enemies will be disappearing before you can even complete your full team rotation. So, that's quite a plus point of using Venti.