Hearthstone: Heroes of Warcraft wants you to get your friends to join card-playing fun.

A new patch for Blizzard’s digital card game behemoth gives players the ability to recruit friends. This program will bring even more players to Hearthstone. It already has a userbase of over 40 million people and leads the $1.2 billion digital card game industry. Players you invite to Hearthstone earn an extra Classic card pack, while the recruiter can “earn free Classic card packs for up to four more recruits.” You can also earn a new Hero portrait, the Shaman Murloc named Morgl the Oracle, if one of your recruits achieves a combined level of 20 across all classes.

Free-to-play games like Hearthstone live and die by the size of their player base. We’ve seen recruitment programs in other free games, but this is the first time we’ve seen one added in Hearthstone.

Alternate Hero portraits started as premium content for the free-to-play game, but Blizzard has used the idea to reward players in fun ways. It previously gave players the Paladin hero Lady Liadrin if they leveled up a World of Warcraft character to level 20. These don’t impact the actual game, as they’reĀ items that show a different character portrait that represents you (and your health), different emotes, and other cosmetic changes.