Avarice

When Avarice dies, her corpse freezes for 9 days, during which time it can't be thawed, harmed by fire, animated, or raised from the dead.

Avarice wields a staff of frost with 10 charges (see "Actions" below).

Avarice is a 10th-level spellcaster. Her spellcasting ability is Intelligence (spell save DC 14; +6 to hit with spell attacks). She has the following wizard spells prepared:

Cantrips (at will): fire bolt (see "Actions" below), mage hand, message, minor illusion, prestidigitation

Level 1 (4 slots): detect magic, mage armor, magic missile

Level 2 (3 slots): flaming sphere, knock, scorching ray

Level 3 (3 slots): counterspell, fireball, fly

Level 4 (3 slots): banishment, fire shield

Level 5 (2 slots): Bigby's hand, Rary's telepathic bond

Ranged Spell Attack: +6 to hit, range 120 ft., one target. Hit: 11 (2d10) fire damage.

While holding this staff, Avarice can expend 1 or more of its charges to cast one of the following spells from it (spell save DC 14): cone of cold (5 charges), fog cloud (1 charge), ice storm (4 charges), or wall of ice (4 charges). The staff regains 1d6 + 4 charges daily at dawn. If its last charge is expended, roll a d20; on a 1, the staff turns to water and is destroyed.

When Avarice is damaged by a creature that she can see within 60 feet of her, she can banish that creature to a frigid extradimensional prison for 1 minute. While there, the creature is incapacitated and takes 5 (1d10) cold damage at the start of each of its turns. At the end of each of its turns, the creature can make a DC 14 Charisma saving throw, escaping the prison on a success and reappearing in the space it left or in the nearest unoccupied space if that space is occupied. A creature that dies in the prison is trapped there indefinitely.