The legion is the body of the church.
It is involved in a massive conspiracy to enforce an alternate standard of behavior while protecting its membership from repercussions within extant systems.
You might cross the wrong person in the wrong way & find yourself disappeared for a traumatic three day stint.
The idea is the legion doesn’t take years from your life. They’ll take a fortnight at most, but those hours will hopefully be sufficiently experience dense that it alters your future behavior.
Also, you’ll know in the future that you’re on legion’s radar.
Rules
Since this could easily be used to impose a Draconian state, the list of core offenses will be short and simple.
To go with the theme of [Yggdrasil] they will be in sets of 13.