This badge was awarded between September 24 (01:15 UTC) and October 21 (06:58 UTC) to people who subscribed 1 regular/gifted/anonymous subscription to any channel streaming in the Dungeons & Dragons category with drops enabled.
It was added to promote Dungeon Masters Campaign 3, the official D&D actual-play series set in Azeroth during the Lich King and Scourge era. The campaign uses the upcoming D&D: World of Warcraft book.