Every Sunday, players can request Epic DNA for one creature instead of the usual Common or Rare requests on other days. 

This feature uses local time. This means if an Alliance is spread over multiple time zones, it's possible that players will start to see Epic DNA Requests from Alliance mates, but cannot request them for themselves just yet.
A special request prompt will appear at midnight local time to alert you you that the feature is now available. Players can make only one request for Epic DNA each week. The request will last for six hours. Once it expires, you will be able to collect Epic DNA if Alliance mates have donated.