Semektet

If a Mummy outside the Web of Faith loses all their Sekhem, they become victims to Semektet oder "the weakening". In that state, they do not regain Sekhem on a regular base and slowly, their other attributes start to degenerate until the Mummy is nothing more than a mindless, degenerated corpse. Furthermore, the Tem-akh starts driving the Mummy back to Egypt, no matter the cost.

The only way to escape the Semektet is an infusion of Sekhem from an outside force or returning to the Web of Faith.

A mummy can use specially prepared bandages to slow the effects of semektet. Constructing the dressing requires two dots in Alchemy, Amulets, or Necromancy and six hours to prepare. Once he's completely wrapped up so that the bandages cover everything but his eyes and mouth, the mummy loses one Attribute dot every three days instead of one every day. The bandages also lower the difficulty of the Willpower roll to resist the tem-akh to 4.

Source

 * Mummy: The Resurrection Rulebook