Swarm-Shifter 13th-Level Mummy King Druid* (CR 16)

Medium Undead (Shapechanger)
Alignment: Usually neutral evil
Initiative: +2 (Dex); Senses: darkvision 60 ft., nature sense, Listen +10, and Spot +10

AC: 27 (+2 Dex, +10 natural, +5 +3 glamered leather), touch 12, flat-footed 25
Hit Dice: 8d12 plus 13d8+21 (131 hp); DR: 5/-
Fort +15, Ref +11, Will +21
Speed: 20 ft.
Space: 5 ft./5 ft.
Base Attack +13; Grapple +20
Attack: +1 keen shocking burst scimitar +21 melee or slam +20 melee
Full Attack: +1 keen shocking burst scimitar +21/+16/+11 melee or slam +20 melee
Damage: +1 keen shocking burst scimitar 1d6+7/15-20 plus 1d6 electricity, slam 1d8+7 plus mummy rot
Special Attacks/Actions: Despair, mummy rot, druid spells
Abilities: Str 24, Dex 15, Con -, Int 9, Wis 18, Cha 19
Special Qualities: Animal companion, a thousand faces, nature sense, resist nature's lure, swarm form (beetle, scorpion, and sand), trackless step, undead traits, vulnerability to fire, wild empathy +17 (+13 magical beasts), woodland stride
Feats: Alertness; Augment Summoning; Combat Casting; Corrupted Wild Shape; Great Fortitude; Improved Natural Attack (slam); Improved Toughnesst; Spell Focus (conjuration)
Skills: Concentration +11, Disguise +5, Hide +9, Knowledge (nature) +1, Listen +10, Move Silently +9, Spot +10, and Survival +6
Advancement: 9-16 HD (Medium); 17-24 HD (Large)
Climate/Terrain: Any
Organization: Solitary
Treasure: Standard

Source: Libris Mortis

A swirling cloud of brown sand ten feet across approaches you rapidly. The dust devil contracts, swirling together and compacting. Suddenly, it coalesces into a withered corpse in funeral wrappings.

The vampire that explodes onto a flock of bats, the mummy that crumbles into a pile of scorpions - these are swarm-shifters, undead that have been granted the dark power to become swarms.

A swarm-shifter appears like a normal undead creature until its body explodes into a swarm. There are many varieties of swarm-shifters, and although some are more common than others, swarm-shifters do not seem limited to certain kinds of swarms by their form of undeath.

Shapechanger Subtype

A shapechanger has the supernatural ability to assume one or more alternate forms. Many magical effects allow some kind of shape shifting, and not every creature that can change shapes has the shapechanger subtype.

Traits: A shapechanger possesses the following traits (unless otherwise noted in a creature's entry).

This is a sample creature derived from a Template.