For my first DMs Guild adventure, I turned a rough start into a high dive into the shallow end of the D&D pool. Don’t try this at home. Read on for the story, but first I’m excited to introduce Battle Walker From the Abyss, my fifth edition Dungeons & Dragons adventure for 17th to 20th level characters. In the adventure, a wizard’s simulacrum asks for help stopping his demon-corrupted original from gaining a walking weapon capable of leveling cities. The quest takes characters across the Abyss, from the market town of Broken Reach, to the demon goddess Zuggtmoy’s fungal plane, and then to a confrontation in an iron fortress over a lake of molten iron. The adventure mixes roleplaying and senses-shattering combat encounters in a plane-hopping mission that tests epic level characters. It typically takes 6-8 hours to play.

The adventure’s rough start came when I opted to create an entry for the D&D Adventurers League open design call for potential tier 4 adventure authors. I wrote about creating for tier 4 and shared my entry. However, my entry failed to interest the judges. When I played my submitted encounter, I learned that it overreached. Blame that on the same creative mindset that leads a player to write a 12-page backstory for new character. For a one shot.

As I created my entry, I imagined it as the slam-bang start to an adventure, which led me to weigh the encounter with details that went nowhere outside my imagination. I suspect the result felt cluttered. Later playtesting also revealed that the encounter included too many moving parts, distractions that I trimmed from the final version.

My encounter featured a magic gate tunneling from a ruined city down to the Abyss—a fantastic location appropriate for legendary heroes. I hoped the setting would create a sense of wonder while enabling mighty characters to flaunt their abilities, but the location proved hard to visualize without an abstract map. The final version includes a map.

The Adventures League team probably needed new tier 4 authors for two reasons:

• Tier 4 adventures can prove difficult to write, especially for a random party of league characters. A table might include all martial types or all spellcasters with wish. Accounting for the possibilities means more work for authors. I’ve learned this first hand.
• Very few D&D players participate in such high-level games. Data from D&D Beyond suggests that 90% of Dungeons & Dragons games stop by level 10. That means level-17-and-up adventures sell far less to comparable low-level outings.

Despite the lack of interest in my encounter, despite the extra effort, and despite the slight rewards of creating a tier 4 adventure for sale, I pressed on to create a complete adventure. More work for fewer sales? Sign me up! Why? Because once I started the story behind the encounter, my imagination failed to let it go. You’re a D&D fan; you know how that goes.

I love the plane-shifting heroics of tier 4. At the highest levels, Dungeons & Dragons lets super-powered characters travel otherworldly realms and battle threats that approach the power of gods. That grand scale lets dungeon masters enjoy the fun of stretching our imaginations’ unlimited special effects budgets, and of pitting the characters against any threat we can dream while feeling confident the players will win.

Battle Walker From the Abyss captures all that, plus a bard’s tale that some playtesters said provided the best part of the adventure. Plus color digital battle maps for some legendary locations.

As for the rough edges in that one encounter, they’re gone. Credit feedback from more than 30 playtesters for a far better adventure than I drafted.

The adventure makes a great tier 4 one shot and also works as a side-quest that fits easily into a high-level campaign. So grab a copy for yourself or as a gift for your favorite dungeon master.

Related: All the Troubles That Can Make High-Level D&D a Bitch To Run, and How To Solve Them

Making High-Level D&D Click: Advice from Alan Patrick, the DM Who Has Run More Tier 4 Than Anyone

Challenging High-level Characters Without Breaking the Dungeon Master