From the introduction: You can create your own DUNGEONS & DRAGONS adventures for play in the PLAGUE OF ANCIENTS campaign set in Icewind Dale, provided you follow the guidelines provided in this document. Crafting a Dungeoncraft Adventure always begins with an established adventure seed (listed below). These adventure seeds are permitted for use during the Plague of Ancients Seasonal Campaign. If you intend to publish your adventure on the Dungeon Masters Guild, it must appear for sale by August 31, 2021. There are no exceptions to this rule.