So as first suggestion, think a way to let user make team and then join together, moba are made to play with people, with clan and if no one of them are free, just join a quickmatch with stranger ally.
I don't know about this new key "system" with W-S and Shift+A/B, if it could be good or annoying for those used to 1-2-3-4 or q-w-e-r, so at last let user change keybind, anyone got his style and letting them using keys they want is better!
About the objective.. that is an hard questioin.. can u tell more about the "background" or "story" of the game? It would be helpfull and would help think about a good idea that fit in the story

Find content
Male