Caul

From the White Wolf Wiki, the most complete White Wolf reference

When a wraith dies, they enter the underworld covered in a plasmic cocoon called a Caul. The caul keeps the wraith docile until it is removed; while the caul is present, the Enfant is in a placid, dreamlike state and generally unaware of their surroundings.

Most Enfants keep their cauls on until another wraith, a Reaper removes them. It is rare for a wraith to remove his own caul, although it is possible in the case of an indivdual with remarkable willpower. Yu Huang, Emperor of the Yellow Springs, apparently never had a caul, but his is the only recorded instance of that happening.

The caul introduces a distinct advantage for the Reaper, and unscrupulous Reapers may keep an Enfant covered until the most advantageous moment. A cauled wraith can be soulforged, Moliated, or otherwise modified without trouble, making extreme abuse easily possible.