Playing card battle game will surely temptate you to spend cash due to high competition from different players around the world. Remember how Magic: The Gathering sold millions of dollars from simple piece of paper. That is the reason why you are addicted in card battling, you must prepare your pocket too as here in country we called it game for rich people only.
That is the truth and that is what really happening in card battle that why big name under gaming company decided to put up an application that everyone can play and spend cash with. But actually they will require them to push marketing hard this time because there are lots of cheats and guides that you can get from the internet for free just like on the popular SquareEnix's Deadmans Cross, if you try to see from different website, you will find that they offer free items through invite codes, as well as tips how you can take advantage from glitches such as having unlimited deck space instead of purchasing it with real cash.
You can also access different gamer's walkthrough, and through their experience you can get the idea on how this game should be played. Just follow tips from players who never spent money in game since you don't want to invest for real cash too.
Also don't forget to join event. One of the most exciting elements of the game is the event that anyone can join to win in-game items. This will ask you different contest such as logo design, referral and lot more, just check their official page to get informed.
There are lots of alternative ways now to dominate the game and since games are meant to be as gold mine for developer, don't get rush to involve your pocket just always use your mind and think about if you enjoy it without spending, I believe that you really don't need you money here.