Underworld Speculation is a two-hour adventure for level 1-4 characters, designed by Chris Lindsay of Wizards of the Coast for use in stores as the Introductory Adventure for Xanathar’s Guide to Everything. It is a D&D Adventurers League legal adventure.

And it’s fun. Really, really fun.

The adventure comes with six pregenerated characters of level 3 that were built using options from Xanathar’s Guide to Everything. They’re not the most optimised characters in existence – and they suffer dreadfully from using the standard Wizards character sheet. It’s not a good format for displaying new options. However, they do give you a taste of the new options.

The fact that the arcane archer has two-weapon fighting may be considered a clue for the setting of the adventure: It’s underwater. Archery isn’t so good.

The adventurers haven’t come to this underwater dungeon willingly, and their task is to escape. They need to navigate winding tunnels and a great cavern to do so, aided by a mysterious magic item that has great power but isn’t demonstrating what it is… not yet, anyway! At least it can give them the ability to breathe water.

The adventure makes use of several new or unusual monsters that the players may not be familiar with, and this adds to the fun of the adventure. There are also a lot of environmental effects to deal with in addition to just being underwater. When you can only hear what someone adjacent to you says,and you can see no further than 10 feet, combats become very tricky, even against weaker opponents… and the enemies aren’t that weak.

There’s a few secrets to be uncovered, and it’s a very challenging adventure to play. It doesn’t feature much roleplaying, as it focuses on the combat and exploration pillars of play.

It’s a moderately complicated adventure to run; I know I missed some important details about the encounters when I ran it, so spending some time reading and sudying it in advance is recommended.

The adventure does feature a few encounters that are placed at the discretion of the DM, but these are limited in scope and make sense for the area in which they’re placed. You’re choosing from three or four ingredients rather than hundreds, and there’s a map to work with. I’m not opposed to this approach to encounters when it’s not hard for the DM to apply; it works very well in this instance.

Quite unfairly, I wanted more stuff in the adventure! It’s already got enough to easily get to its two hour running time, but I wanted a few more things to do in the second half – particularly more details on the structures the adventurers find.

I believe it’ll become available on the DMs Guild in future, but for now it’s a store exclusive.

This is an excellent adventure, and a wonderful introduction to the world of the Xanathar!