Dungeons & Dragons designer Skip Williams leads us deep underground for a look at a brand-new monster for D&D: one that’s sure to cause its share of mayhem for any party unlucky enough to cross its path. (As a special treat, we’ve included the full entry from the Monster Manual as it currently reads.)

"This is one of the brand-new monsters we created for this edition of the game. These creatures can literally build dungeons on their own. Their inclusion introduces another acid-using monster into the game (keep those protection from elements spells handy) and presents players with a creature they can negotiate with (at least sometimes)."

Delver

Huge Aberration
Hit Dice: 15d8+75 (142 hp)
Initiative: +5 (+1 Dex, +4 Improved Initiative)
Speed: 30 ft., burrow 10 ft.
AC: 14 (–2 size, +1 Dex, +5 natural)
Attacks: 2 slams +17 melee
Damage: Slam 1d6+8 and 2d6 acid
Face/Reach: 10 ft. by 20 ft./10 ft.
Special Attacks: Acid
Special Qualities: Acid immunity, corrosive slime, tremorsense, stone shape
Saves: Fort +10, Ref +6, Will +11
Abilities: Str 27, Dex 13, Con 21, Int 14, Wis 14, Cha 12
Skills: Intuit Direction +9, Knowledge (geology) +9, Listen +13, Move Silently +19, Spot +13
Feats: Alertness, Blind-Fight, Improved Initiative, Power Attack, Sunder
Climate/Terrain: Any underground
Organization: Solitary
Challenge Rating: 9
Treasure: None
Alignment: Usually neutral
Advancement: 16-30 HD (Huge); 31-45 HD (Gargantuan)

These bizarre creatures live in the depths of the earth, burrowing through solid stone with a corrosive slime they secrete from their skins.

Delvers are shy and mostly inoffensive creatures, but rogue specimens with murderous streaks are not unknown. They feed on stone and may even devour creatures such as xorns and earth elementals.

A delver resembles a cross between a giant slug and a sea turtle. It has a teardrop-shaped body that glistens with slime, mottled gray, brown, and ochre all over. Two great flippers tipped with blunt claws sprout from the forebody. The creature feeds by dissolving rock with its slime and shoving the resulting goo under its body, the underside of which is almost all mouth.

Delvers eat rock but enjoy various nonmetallic minerals as seasonings in the same way that humans enjoy spices. Adventurers might secure information and assistance from delvers by offering them tasty minerals (usually gems) or pick-me-ups (such as coins). Metal is an intoxicant to delvers. Some, however, become addicted and are a menace to miners and anyone who carries metal equipment.

Delvers speak Terran and Undercommon.

Combat

Delvers prefer to fight from their tunnels, which they use to protect their flanks while lashing out with their flippers.

A delver expecting trouble may honeycomb an area with tunnels, leaving most closed with layers of stone 1 or 2 inches thick. The delver can quickly dissolve the stone cover and pop up to attack unexpectedly.

Corrosive Slime (Ex): Delvers produce a mucuslike slime that contains a highly corrosive substance. The slime is particularly effective against stone.

A delver’s mere touch deals 2d6 points of damage to organic creatures or objects. Against metallic creatures or objects, a delver’s slime deals 4d8 points of damage, and against stony creatures (including earth elementals) or objects it deals 8d10 points of damage. A slam attack by a delver leaves a patch of slime that deals 2d6 points of damage on contact and another 2d6 points of damage in each of the next 2 rounds. A large quantity (at least a quart) of water or weak acid, such as vinegar, washes off the slime.

An opponent’s armor and clothing dissolve and become useless immediately unless the wearer succeeds at a Reflex save (DC 22). Weapons that strike a delver also dissolve immediately unless the wielder succeeds at a Reflex save (DC 22).

Creatures attacking the delver with natural weapons take damage from the slime each time their attacks hit unless they succeed at Reflex saves (DC 22).

Tremorsense (Ex): A delver can automatically sense the location of anything within 60 feet that is in contact with the ground.

Stone Shape (Ex): A delver can alter its slime to temporarily soften stone instead of dissolving it. Once every 10 minutes, a delver can soften and shape up to 25 cubic feet of stone, as stone shape cast by a 15th-level druid.