You start out with lots of Webspinners, and keep getting more throughout the battle. You can get the rare class spell card, but those seem few and far between. It has been updated with the latest cards from the current expansion, so that’s one “perk”.
So, pick your favorite class, and get to work on that free pack. This is a “one and done” for me. Not one of my favorite brawls. Have fun and enjoy your free cards!