Back in the day, White Dwarf magazine was the British answer to the Dragon, and its regular "Fiend Factory" column was a source of many monsters for early D&D games. In fact, the first edition Fiend Folio (1981) was largely a collection of monsters submitted to WD. This 3e conversion is part of an ongoing project to resurrect some interesting WD monsters that, for one reason or another, fell by the wayside.

The green worm was a submission of Ghee Bowman and appeared in White Dwarf 17 (Feb/March 1980) , in a second Fiend Factory installment detailing monsters that very nearly made it into the Fiend Folio—complete with line art by some of the iconic Fiend Folio artists. Another one of Bowman's creations, the rothé, was more lucky and made the final cut for the Fiend Folio.

Although purple worms are considered magical beasts in 3e, the vermin monster type seems to make much more sense for the green worm.

The massive, writhing worm rears up, its green segmented form glistening with slime.

Green Worm CR 3

A Huge green worm

Always N Large vermin

Init -1; Senses Listen -1, Spot -1

AC 14, touch 8, flat-footed 14
(-1 size, -1 Dex, +6 natural)

hp 26 (4 HD)

Immune mind-affecting effects

Fort +6, Ref +0, Will +0

Spd 20 ft. (4 squares), burrow 10 ft., swim 10 ft.

Melee tail +6 (2d6+4 plus poison) and bite +1 (1d10+2)

Space 10 ft; Reach 10 ft

Base Atk +3; Grp +11

Special Atks improved grab, poison (DC 14), swallow whole

Abilities Str 19, Dex 9, Con 15, Int -, Wis 8, Cha 8

SQ vermin traits

Environment underground

Organization clutch (1-6)

Treasure standard

Advancement 5-8 HD (Large), 9-12 HD (Huge)

Improved Grab (Ex) To use this ability, a green worm must hit with its bite attack. It can then attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can attempt to swallow the foe the following round.

Poison (Ex) Injury, Fortitude DC 14, initial damage 1d2 Str, secondary damage 1d6 Str. The save DC is Constitution-based.

Swallow Whole (Ex) A green worm can try to swallow a grabbed opponent of two sizes smaller than itself by making a successful grapple check. Once inside, the opponent takes 1d8+4 points of crushing damage plus 2 points of acid damage per round from the worm's gizzard. A swallowed creature can cut its way out by using a light slashing or piercing weapon to deal 10 points of damage to the gizzard (AC 12). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out. A Large worm's interior can hold 2 Small, 8 Tiny, or 32 Diminutive or smaller opponents.

A small relative of the purple worm, its name exactly describes this creature. Its normal maximum length is about 20 feet.