The ELO tournament in Urban Rivals is one of the only few ways a player might win those coveted Collector cards in the game. The other two being buying the cards themselves (which can be worth millions of in-game currency) or participate in official once-in-a-blue-moon games/events which are hosted by certain moderators.
Going back to ELO, there's an important thing to remember before joining in on the fun of this weekly event, and that is how to create a winning ELO Deck. There are many cards which are banned from ELO play. Add to that, every week, one clan is banned from the ELO tournament entirely. That is a pretty tough situation, especially for ELO newbies.