Mythic Odysseys of Theros - Mechanics and Features

So, what new mechanics does the Theros book introduce?

First, we can get a couple of obvious ones out of the way:

Theros has several new races, as well as some that have been printed in other sourcebooks. Notably, humans are the only player race from the Player's Handbook canonically found in Theros.

Minotaurs, previously published in Guildmaster's Guide to Ravnica, are fierce warriors and wandering marauders.

Centaurs (also found in Guildmaster's Guide to Ravnica) are spiritual nature-worshippers who avoid urban civilization generally.

Tritons (also found in Volo's Guide to Monsters) are seafaring people who live beneath the tides, seeking knowledge and trading with other peoples.

Leonin are lion-people who live in Theros' open grasslands, generally living in tight-knit packs.

Satyrs are rowdy hedonists who love to revel and express themselves artistically (like Centaurs, Satyr count as fey rather than humanoid.)

Theros also introduces two new subclasses:

The Bardic College of Eloquence allows your bard to be a sort of poet or arguing philosopher, with a number of ways to make your bardic inspiration more reliable and effective (also, by level 3, you can't roll lower than a 10 on Persuasion and Deception checks.)

The Paladin Oath of Glory is all about dedicating yourself to feats of heroism and strength, inspiring those around you.

Moving on to more unique mechanics:

Piety is a stat similar to renown, which allows you to increase your favor with your chosen god. By honoring your chosen deity, you can start to earn various benefits. For instance, with 10 piety to Heliod, the God of the Sun, you can cast Daylight once a day. Like ranks in the Ravnican guilds, these range from minor bonuses at 3, ramping up to permanent ability score increases at 50.

Additionally, there are a number of Supernatural Gifts that Theros characters start with (though the DM might reward these if the player pleases a god who can bestow it.) These are kind of like minor (or not so minor) level-1 feats, or sort of similar to subraces or Eberron's Dragonmarks. For example, one of the most extreme ones is "Anvilwrought," which almost makes you a Warforged, marking you as being made by Purphoros, the God of Craftsmanship.

The book also has a number of new monsters (including Mythic monsters, who have essentially an "enrage" mode in which they become more dangerous after your initially "defeat" them) as well as a short intro adventure and some sample adventures and maps based on the various gods (similar to the guild-based adventures in Ravnica.)

There's definitely a lot to pillage from this book, especially if you want to make the gods a more central piece of your own setting. I love omens and prophecy in fantasy, and you can make that a big part of any character's (or every character's) personal journey through your campaign.