Level: 6; Hit Dice: 18 (63)

THAC: +6 ( also see Combat below)
Attacks: 3
 Claw: 1d8+6
 Claw: 1d8+6
 Mandibles: 1d6+2 ( clamp and lacerate)
 2d8+6 ( gore)
 4d6+8 ( charge)
 or Teeth: 1d10+6

INT: Average; Morale: 14
Size: Average 2.43 meters (8 feet) tall;
1.52 meters (5 feet) wide;
2,041 kg (4,500 lbs) in weight

XP: 1800

Frequency: Rare
Organization: Solitary or Mated Pairs
Activity Cycle: Any
Tech Level: 0
Climate/Terrain: Underground
Diet: Carnivore
Artifacts: B

Physical Mutations Total Carapace (18),  Nocturnal (D), Heightened Smell, Heightened Hearing
Mental Mutations Confusion (16), Description:

Umber Hulks are large bipedal creatures with 2 sets of eyes. They have huge mandibles, reminiscent of giant Stag Beetles. They are black in overall color, and their jagged mandibles and claws blend into a discolored ivory.

The Umber Hulk is the rhinoceros of the subterranean world. They are in a constant state of rage, burrowing around in eternal search of prey. With their wicked claws, they burrow through loose earth at an alarming rate, and even through solid stone at an unbelievable pace.

The creatures are fearless, except for extremely bright lights, from which they may flee, depending on their rage or hunger at the moment. Normal light will only cause the beasts to suffer the sight penalties of their Nocturnal mutation. (A Photogeneration mutation attack on an Umber Hulk would be at intensity 1.5 x MP modifier instead of just 1 x MP modifier).

Combat
Confusion mutation: These ferocious beasts use their Confusion mutation whenever possible in an attempt to immobilize their prey. While they may look like dumb animals, they are in fact reasonably intelligent, and smart fighters. They have instinctively developed many ways to deal damage to their foes.

The Umber Hulk's claws that are so efficient at rending even stone are also used to deadly effect in combat.

A Hulk's third attack may be by either mandibles or teeth, never both in the same round. 

Teeth: If so desired a Hulk can spread its mandibles wide enough for them to miss its prey and thereby deliver an immediate vicious bite with its razor sharp teeth.

Mandibles: An Umber Hulk may thrust its head in close combat and gore an opponent with its strong mandibles.

Charge: It may also choose to deliver a devastating charge attack.

Clamp: Yet another favorite tactic of the Hulk is to use its mandibles to clamp down on its victim, lacerating and immobilizing its adversary. If an opponent is so caught, the Hulk can choose to continue to clutch its prey. In subsequent rounds where the victim is clutched, the Hulk will be unable to attack with its engaged mandibles, but will be able to rend with both its claws, and deliver a savage bite attack, all at +10 THAC instead of +6.

Other: Skilled armorers can cure and shape armor from the hide of the Umber Hulk. Such armor will give a +6 AC, equivalent of good quality Banded Mail.

Converted from TSR's Advanced D&D Monster Manual.