It's the dream of hearthstone players to "go infinite", to be able to win so often in the arena that the gold you win pays for the entry fee and you can play arena for free as much as you like.
Arena is a bit tricky at first, my first attempt as drafting a deck was awful, almost everything cost 4 mana and I didn't glance at the graph at the bottom of the screen until after I'd picked all the cards.
I think though that I'm beginning to get the hang of it:
You can't quite see all the cards in that picture, I also have an Archmage Antonidas and a pyroblast.
In fairness I'm not infinite yet: my recent results are 4-3, 8-2, 3-3, 3-3, 7-3 and 8-0. Still feels pretty exciting to be doing well after only a week.
Eagle-eyed readers may spot that this damn game is keeping me up far too late!