"Win the deck" events are aimed at new players/beginners. Two players get the 1500-point quickstart armies from a starter deck and play against each other...the winner keeps the deck.
That sounds perfect Chad

... Does it cost like 7.50 per person? Also, will I need to sign up for "win the deck" though gencon, or just show up at the YMG booth?
Heh. It's a bit better than that. We're required to charge (I believe) one generic ticket, which is about $2. We don't charge anything on top of that...essentially we're saying, "If two people at GenCon want to invest an hour of their time playing Battleground we will give them a deck in exchange."
You won't need to sign up...we can run up to 10 at a time and it's unusual for us to fill up more than one or two time slots (out of maybe 12) over the course of the Con.