Ankheg

An ankheg resembles an enormous many-legged insect, its long antennae twitching in response to any movement around it. Its legs end in sharp hooks adapted for burrowing and grasping its prey, and its powerful mandibles can snap a small tree in half.
These subterranean ambush predators usually hunt alone, but they have been observed to form clusters or hives when there is enough sustainable game. These hives usually do not last very long, since they drain the surrounding landscape of all prey in a short time, or attract the attention of adventurers.

Lurkers in the Earth

The ankheg uses its powerful mandibles to dig winding tunnels deep beneath the ground. When it hunts, an ankheg burrows upward, waiting below the surface until its antennae detect movement from above.Then it bursts from the earth and seizes prey in its mandibles, crushing and grinding while it secretes acidic digestive enzymes. These enzymes help dissolve a victim for easy swallowing, but the ankheg can also squirt acid to take down foes.

Bane of Field and Forest

Although ankhegs receive a certain portion of their nutrients from the soil through which they burrow, they must supplement their diet with fresh meat.Pastures teeming with grazing livestock and forests rife with game are an ankheg’s prime hunting grounds. Ankhegs are thus the bane of farmers and rangers everywhere.
While they can be found in a variety of environments and conditions, these insectoid monsters are more active in warm climates. In cold climates, they hibernate during a large amount of the coldest seasons. 

Earthen Tunnels

As it burrows through earth, the ankheg leaves a narrow, partially collapsed tunnel in its wake. In these tunnels, one might find the remnants of molted ankheg chitin, hatched ankheg eggs, or the grisly remains of ankheg victims, including coins or other treasures scattered during the creature’s attack.

Ankheg Loot

• 1 Ankheg Claw. Acts as a shovel. Can be carefully crafted (Smith's Tools) into a Greatsword that deals an additional 3 (1d6) acid damage on a hit.
• 1 Vial of Ankheg Acid. Acts and a Vial of Acid, listed in the Player's Handbook. Can be crafted (Alchemist's Supplies) into a Vial of Potent Acid (as a normal vial, but deals 10 (3d6) acid damage on a hit).
• 1 Ankheg Chitin. No immediate use. Can be mastercrafted (Smith's Tools) into a set of Plate Armor +1.