I actually agree with you, if you look on smite stuff, Bastet and Hun batz have the 3rd and 4th highest win rate in arena. Assassins are important. I would just say a tank is the Most important as the cc is what lets everyone else hit. Once you have a great tank, you want a variety of things hitting the targets, assassins included. I was just saying 3 mages can work, if right tank is in place.
I'm actually mastering bath right now, he's awesome in team fights.