It's a decentralize game on the steem blockchain. You basically buy cards using steem/sbd and battle them with other users. The battle will be automatic and depends on Luck, placement of cards, level of cards, and rarity of cards. After competing a season, you will receive a certain amount of cards as rewards depending on your league. You can also sell, trade, and buy cards from the market. One of my friends here received a gold card from the competition and sold it for 200 steem. It's a fun game if you like to collect and trade cards, but those with money have more advantages. The goal is to help people like myself receive more cards. Most of the cards are cheap tho.
RE: Steem Monsters Giveaway #2 (For Beginners, but anyone is welcome to join)