there is no configfiles for only the arena. you can't choose hero and cards in arena.
if there was, its WR would be very low. running the bot in arena is goldwaste.

and...plz...spend cash. this is TCG.
of course you can play with only common cards.
but there is no one who make decks or configfiles with only common card.
you need some original,adventure and expansion cards whatever you play the casual or ranked or arena.