Announced today during the opening ceremonies at this year’s Blizzcon 2016, a new skin for Genji will be available to all players who play fifteen games of Heroes of the Storm with one or more of their friends between November 15th and January 4th. In addition to the skin players will also get an Oni Genji portrait and spray in Overwatch while also unlocking Zarya in Heroes of the Storm. Zarya was added to the MOBA back in August.
If you decide to play up to thirty games in Heroes of the Storm with a friend, you can unlock additional rewards. Read more about the Nexus Challenge.