The Jackal-Headed are one of the more interesting Decrees as it seems to stem from a different angle from the others. If all the other Decrees stem from a higher calling, whether to emotion, action, purpose or knowledge, the Jackal-Headed form their Decree in a form of an oath of eternal service.
Theirs is a dedication different from the Bull-Headed in the sense that they are not self-determinators, but rather willing to submit to the will of the Judges of Duat. They are subservient to their eternal masters, and are perhaps the most driven of all as long as it is in line with what the Judges want from them.
Their form of Decree means that the Jackals are the most intimately familiar with the ways of the Judges, and the mysticism that surrounds it. They are fearless and difficult to distract from a cause. I can imagine that this can lead to interesting situations where a Jackal starts developing doubt and stray thoughts as his Memory increases and he learns to question the Judges.
That said the Jackal-Headed restore their Pillars by exemplifying the way of shadow. Revealing hidden truths, confronting and overcoming fear will empower them. However, if they manage to reveal a truly profound lie on behalf of the Judge he serves then his pillar is restored in full.
Of all the five Decrees, the Jackal-Headed are interesting, but share very close overlaps to the Su-Menent. Both have immunity to fear in one shape or form, and stacking these might end up being less than ideal. Still the concept itself is sound and it makes sense that the Jackal-Headed would be part of the Funerary Guild.
Now that we’ve gone over the five Decrees, I think it’s safe to proceed with character creation. We’ll see what it takes to put together a decent Mummy: Character and hopefully get to see the various systems interacting.