Loki's back (avengers fan fic)

In a time of great need a band of superhero's were forced to work together not many people thought they could pull it off. This band of six hero's were called the Avengers. They defeated Loki and his other worldly army. But what would happen when this team are not capable of defending the world again? Who will help them? The world is facing this pressing problem Thanos and Loki are back with a bigger army and a better plan.