Piety

Piety is a system detailed in the D&D 5e Sourcebook: Mythic Odyssey of Theros. The system revolves around a sort of currency relating to your characters' relationship with various Gods. Piety score is a way to track this system, and is awarded to you by a Game Master, Story Master, or Combat Master when you do something to advance the god’s interests or behave in accordance with the god’s ideals, and acts as a reward for good Roleplay.

The gods expect great deeds from their champions, so your piety score typically increases only when you accomplish a significant goal (such as the completion of an adventure), make a significant sacrifice of your own self-interest, or otherwise when the Game Master sees fit. Each god’s description in the Sourcebook includes a discussion of the god’s goals and ideals, which your DM uses to judge whether you earn an increase in your piety score.

Most DMs will award a piety score increase by about 1 in these cases, and usually only at the end of an Adventure or Quest. Keep in mind that in most cases you can not have piety with multiple Gods, and that your score with one God can go down if another one goes up. This is different then the Source book's interpretation, as it assumes you choose to be only one god's Champion, when you can be a champion of the whole pantheon.

Not every hero chooses the life of a divine champion. Some may be known for rejecting the worship of gods. If you don’t devote yourself to a god, you don’t have a piety score and you gain no rewards for piety, but you don’t suffer any negative consequences.

Being pious and acting according to the Deities of Theros is similar in ways to how Warlock Patrons work. You are gifted power by certain gods with the expectation that you will accomplish great things in their name, remain pious, and generally be loyal to their goals. This can come with the caveat of a God making a demand of your character, or alternatively, may come with the bonus of another god offering you their own rewards should you sway from your current path.

First God

During Character Creation, you should list and inform the DM and Sheet Masters about what God you are first worshiping if you are in fact worshiping a god. You will then get a role relating to either the Deity you are worshiping, such as an Heliod role, or an unbeliever role. You can be a Champion of multiple gods, provided those Gods do not conflict with each other. However, your Piety Score will always cap at 50, even when spread among multiple Gods.

Additional Gods

If you chose to become pious towards an Additional God, become Pious to your first god, you must submit this change in piety as if it was a Downtime Submission. Spending a number of Downtime Days equal to your level to earn the eye of this God. Additionally, you may earn the Eye of a God during an activity, in which case you will be asked to submit this Downtime activity without the cost. Once your submission is approved, you will be given the role of the deity. You cannot loose the eye of a God once you have gained it, without directly doing something against their interests.

The Gods bestow favors on those who prove their devotion. When your piety score crosses certain thresholds—3, 10, 25, and 50—you gain a benefit detailed in the sections describing the gods’ champions in chapter 2 of the Source book. If you choose the Oracle supernatural gift, you gain different rewards for your piety score, instead of the ones normally granted by your god.