Always in a disadvantage


I just don’t the rules of the Battle Arena mode. It seems that I’m always at a disadvantage.
My opponent can always start first, when my creature has lost my opponent start again, if his creature lost he can start (wtf), sometimes he can strike twice in a row, my stun never works, my opponent stun is always effective in my disadvantage. There is simply no way for me to win. Can someone explain to me how it happens?