So how much power?

On our own - none. As a willing instrument of the Lord - ALL. We only have to look at what the 12 Apostles and 72 Disciples did at Jesus' command - healed the sick, cast out demons, raised the dead, and shared the Good News. They are no different than us other than maybe they trusted fully and cooperated completely. Jesus wants His creation to blaze. Are you willing to help start the fires? Alleluia, Alleluia!