Ironically, the one who signs somone as inviter is the one who is really "Sponsoring" something. There is no real sponsorship (unless some guild or indivifual freewillingly off the official system does something like that).
The benefit of inviting people is that inviter gets 10% of any credits his invitee buys. Invitee does not lose them but the system generates extra credits for the inviter. This is the normal promotion system used in the web scheme; get more customers = you get some benefits.
The Urban Rivals team is made by lovers of all kind of Collectibles Cards Games and Trading Cards Games like: Magic the Gathering, Dominion, Vampire, Yu-Gi-Oh!, Pokemon, Wakfu TCG, Assassin Creed Recollection, Shadow Era, Kard Kombat and Might & Magic Duel of Champions.