Do existing benefits of the piety system continue to work in planes other than Theros?

Question

The Mythic Odysseys of Theros book introduces mechanics for Piety (p. 36):

The strength of your devotion to your god is measured by your piety score. As you increase that score, you gain blessings from your god.

Nowhere does it mention if this is limited to a character's presence on the plane of Theros, where the gods reside.

While the source book doesn't mention moving between planes, is there any indication that existing benefits of the piety system stop if the characters leave that plane? I'm asking in the context of the Magic: the Gathering setting, where interplanar travel is possible.

My default assumption is that it's unspecified and possibly unanswerable, but I'm happy to be proven right/wrong.

Answer 1

It is up to the DM.

While researching this question, I have found nothing definitive, but I have found some things that can help guide a DM toward a ruling.

The gods get their power from you, not the other way around.

In the description of Nyx, the realm of the gods, we see this description of the gods and their power:

Though the gods live in a veritable paradise, they can’t sever themselves from the mortal world. To do so would be to lose the faith of their followers, the source of their magic and a power they will not relinquish.

The power of the gods is contingent upon the faith of their followers. Your faith in your god is the source of the power with which the god dispenses blessings.

The influence of the gods of Theros extends only to Nyx, the Underworld, and the Mortal Realm.

In the introduction to Mythic Odysseys of Theros, we see:

Notably, though, these gods have influence only over Theros and the two planes connected to it: Nyx, the starry realm of the gods, and the Underworld, eventual home of all die.

A particular god's active influence certainly does not extend beyond these three realms.

The DM must decide if the god’s blessings are dependent upon constant connection to their follower, or if once given, they are intrinsic to the follower.

If we rule that the blessings depend upon active communion with the god, then planar travel to any plane other than Nyx or the Underworld will sever that communion.

But if we rule that a blessing becomes an intrinsic or innate power of the blessed creature, that it depends only on the constant faith of the blessed follower, the blessings would continue to function while trekking to exotic planes of existence.

It can go either way, I think.

Answer 2

Unspecified doesn't mean unanswerable.

Nothing specifies that a cleric doesn't lose their powers when they change planes. However, since nothing specifies that they do, then you continue with your cleric powers.

Class features, skills, bonuses and the like are present until they are specifically removed. So unless there is a rule stating that gods of Theros cannot have any influence on other planes, then the boons they grant would continue to function.

Also worth noting is the DMG section on blessing, which piety is similar to an expanded and codified version of:

A character retains the benefits of a blessing forever or until it is taken away by the god who granted it. Unlike a magic item, such a blessing can’t be suppressed by an antimagic field or similar effect.