Where are your 7 stars?
Your roster will be changing very quickly. Try to learn what you can about every new champ you get. You can find videos briefly breaking them down and youll get an idea of how useful they are. As your roster develops and you learn the game, you will then realize what your roster is lacking and what/who you need. Nick Fury is an absolute win tho. That 4* Gladiator will serve you well for a while just by him being a 4*. Gladiator is a pretty garbage champ tho, so he will not be your bread and butter for long.Gamora and Colossus are good too.