| Hit Dice: | 48d10+432 (696 hp) |
| Initiative: | +9 |
| Speed: | Fly 60 ft. (12 squares) (perfect) |
| Armor Class: | 23 (−8 size, +5 Dex, +16 deflection), touch 23, flat-footed 18 |
| Base Attack/Grapple: | +48/— |
| Attack: | Incorporeal touch +46 melee (4d6 electricity plus 4d6 sonic) |
| Full Attack: | Incorporeal touch +46 melee (4d6 electricity plus 4d6 sonic) |
| Space/Reach: | 40 ft./15 ft. |
| Special Attacks: | Engulf, thunderclap |
| Special Qualities: | Blindsight 90 ft., darkvision 60 ft., defensive shock, immunity to electricity and sonic damage, incorporeal subtype, low-light vision, spell resistance 30 |
| Saves: | Fort +37, Ref +33, Will +22 |
| Abilities: | Str —, Dex 21, Con 28, Int 14, Wis 19, Cha 42 |
| Skills: | Hide +33, Listen +47, Search +42, Spot +47, Survival +45 |
| Feats: | Alertness, Blind-Fight, Combat Expertise, Combat Reflexes, Dodge, Endurance, Great Fortitude, Improved Initiative, Iron Will, Lightning Reflexes, Mobility, Run, Spring Attack, Skill Focus (Hide), Track, Weapon Focus (incorporeal touch), Whirlwind Attack |
| Environment: | Temperate land |
| Organization: | Solitary or pod (2–4) |
| Challenge Rating: | 21 |
| Treasure: | None |
| Alignment: | Always neutral |
| Advancement: | 49–144 HD (Colossal) ♊ |
| Level Adjustment: | — |
Thunder worms are sometimes called living storms, for they float about in clouds, and their bodies course with electricity and sonic energy.
Some sages and adventurers compare thunder worms to purple worms, but the similarity ends in the wormlike shape shared by both monsters. Thunder worms are incorporeal, with cloudlike bodies that resist material attacks. They look like long clouds of mist that range from wispy white to threatening black in color, with many shades of gray in between. Lightninglike discharges dance constantly through their forms, and they make a soft rumbling sound when agitated.
Thunder worms do not speak, but they understand Common, Auran, and Giant.
A thunder worm tends to initiate combat with its thunderclap attack; then it closes on its foes to touch and engulf them.
Engulf (Ex): As an incorporeal creature, a thunder worm can position itself so that it occupies the same spaces as its enemies—a fate potentially far worse than being swallowed by a purple worm. This attack affects as many creatures as will fit within the cloud worm’s facing (a 40-foot cube). Target creatures must make a successful Reflex save (DC 43) or take electricity and sonic damage as if hit by the cloud worm’s incorporeal touch attack. Creatures that fail their saving throws take damage each round that they remain within the cloud worm’s body, with no further opportunities for saving throws. Creatures that make a successful saving throw must continue to save each round that they remain within the worm’s body, taking damage if they fail (and thereafter receiving no additional saving throws until they move out of its body).
Thunderclap (Ex): A thunder worm can produce a thunderous boom as a standard action. Creatures within 30 feet of the worm must make a Reflex save (DC 43) or take 24d8 points of sonic damage. After producing a thunderclap, a thunder worm must wait 1d4 rounds before doing it again.
Blindsight (Ex): A thunder worm maneuvers and fights not only by sight, but also by using hearing and smell to ascertain its surroundings. See Blindsight.
Defensive Shock (Ex): An opponent that uses a metal melee weapon or a natural weapon to deal damage to a thunder worm must make a Reflex save (DC 43) or take 2d6 points of electricity damage from the creature’s body.
Source: Fiend Folio, page 176. Changes applied as per the D&D® v.3.5 Accessory Update. Corrected the DC of the Reflex save of Defensive Shock special attack from 34 to 43.