Ankheg

Ankhegs are insect-like creatures living underground between 10-20 feet tall, coming above ground to find prey. The only warning the player gets is that areas where these creatures are, there can be heard strange sounds, but it is not possible to determine how many are there. In areas where they live, caution is advised and fight only one or two of these creatures at a time. They can use melee attacks and ranged attacks, but their ranged attacks, which consists of a projectile of green acid is the most dangerous, able to kill the target instantly or doing 10-25 points of damage. When they are killed, they always drop a ankheg shell, weighing 100lbs, and some random loot of high quality.

Tactics
Tactic one

You need at least two warriors with a lot of hitpoints and good weapon&armor. They will fight the ankhegs in melee combat. The other group members use ranged attacks and it might be handy to have a lvl 5 mage who is able to cast chromatic orb, which can stun the target for three rounds. You also need someone who can take the shells. Minsc has a carrying capacity of 320 lbs or you can create a protagonist which can also carry a lot of weight.