Keith Baker, the creator of the Eberron campaign setting, has co-authored a new supplement that adds a ton of new character options, dragonmarks, and subclasses for Fifth Edition play. Baker and Ruty Rutenberg released Morgrave Miscellany on the DMs Guild, a website partnered with Wizards of the Coast that allows third party creators to release supplements using official D&D intellectual property. While Morgrave Miscellany is technically an "unofficial" addition to Eberron, the fact that it's co-written by Baker means that a lot of people are giving it a lot of attention.
Morgrave Miscellany is divided into four parts. The first contains new subclasses loosely based around the prestige classes from third edition play, and also explains how existing classes fit within Eberron society. Chapter two adds a number of new subraces, including a brand new type of Warforged known as the Dragonforged. Chapter 3 provides DMs with some resources and tools to better craft a story within Eberron's unique brand of "fantasy noir," while Chapter 4 provides some "Zero Level" hooks meant to introduce players into the world of Eberron and develop into a team without the benefit of character classes to guide them.
Of course, the biggest draw of Morgrave Miscellany are the new subclasses, and there's a few really cool ones in this supplement. The Bone Knight is a necromantic Fighter class with access to a handful of spells and the ability to summon skeletal horses and turn their bones into armor and weapons. The Barbarian "Path of the Extreme Explorer" is basically fantasy version of Bear Grylls, an explorer used to surviving in extreme conditions that can use their adrenaline to overcome certain obstacles. The Sovereign Cleric domain is also pretty cool, as it acknowledges the full pantheon of gods instead of being dedicated to a single deity.
All in all, this is a great addition to Eberron, especially for those who are eager for more content after the release of the Revised Artificer. This is basically a full second Eberron publication, one that serves as an impressive addition to the foundation set by Wayfinder's Guide to Eberron.
Morgrave Miscellany is available on the DMs Guild for $14.95.