Hook: the Three Diadems of Azzagrat

[Stix]

The Three Diadems of Azzagrat
One of these, the Mantle of Horns, is in the hands of the Tai Harith, a cult of Graz'zt based in Sigil. They are currently searching for a female descendant of the Abyssal Lord -- the only sort of person who can truly unlock the Mantle's power -- to don the crown and lead the cult as a proxy of Graz'zt himself.
Relevant PCs: Wraith and Niloufar are both capable of wearing the Mantle of Horns.

[Stix]

Characteristics of the Mantle of Horns:

Detect Invisibility by concentration
Detect Poison 3/day
Detect Charm 3/day
Dispel Magic 2/day
Augury 1/day
Nondetection 1/day
Never attacked by Viper Trees
Command Tanar'ri (as Command Undead)
+3 protection
Regenerate 2 HP/turn
25% Magic Resistance

Duplicate Spell Effect by sacrifice
1st: Bloodletting for 25% HP loss
2nd: Dismember intelligent being (loss of digit, ear)
3rd: Dismember intelligent being (loss of hand/foot, eye, nose)
4th: Dismember intelligent being (loss of limb, tongue, genitals)
5th: Sacrifice intelligent being
6th: Sacrifice two intelligent beings
7th: Sacrifice three intelligent beings