BOZ
Creature Cataloguer
Also…
Did we discuss adding something regarding breaking weapons?
this passage should help illustrate why I don’t think a physical attack is necessary:
if we give it anything, it should not be terribly damaging. The slime and heat should take care of most attackers, and if it comes up against something that is immune to acid and fire, then that is its problem.
finally wrote up the flavor text:
This appears to be a cooled-down, oblong lava formation at first. It begins to move, giving it the appearance of a slug made from black granite. Even at a distance, the heat generated by this creature is intense, and its acidic odor of ammonia is powerful.
The horgar is an immense, powerful creature that eats its way through solid rock to create subterranean tunnels, passageways, and caverns. It lives deep within the earth, spending all of its time tunneling through and eating rock.
Some races call this creature a stone-eater, though it is commonly known by its dwarven name of horgar, and its less commonly known gnomish name of storgin (both of which mean “stone-eater”). These mysterious creatures are sometimes worshipped as gods by primitive lesser races. Some races try to tame horgar, to use the creatures to make passageways as they want and to attack enemies. Such captive horgar are kept in glass-lined pits, and their keepers (called horgarin in the Dwarf tongue) slip long, thin spears through the cracks in their skin to prod the sensitive flesh below. Thus, a horgarin may control which direction a horgar moves, though a careless handler is likely to lose his life to his charge.
A horgar’s chitinous skin is made from five-foot thick stone, with great cracks that divide it into large plates. These plates shift and slide while the creature moves, creating small fissures from which the horgar secretes its super-heated slime. A horgar also constantly generates searing heat from its body, reaching between 400 and 500 degrees. As a horgar moves, it grinds against the tunnel walls it makes, as its slime and heat melt the rock and fuse it into new formations. The only exposed part of a horgar is its round head, located at one end, which just seems to be a lump of softer-looking stone.
It is easy to detect a fresh stone-eater tunnel, as it remains hot for many hours. Tunnels and other new formations cut through hard rocks such as granite remain permanent, while passages made in softer stone such as sandstone collapse as the horgar moves through them.
A horgar is at least 30 feet long and can grow up to 100 feet in length, and weighs X tons.
COMBAT
A horgar is not an aggressive creature, by any stretch of the imagination. A horgar does not recognize most organic things as living creatures, and tends to continue moving whether or not something is in the way. If provoked or attacked, a horgar will usually try to leave. If it cannot run away, a horgar will turn to fight. It can squirt acid from its head up to 20 feet away. It will try to flee again at the first available opportunity.
Did we discuss adding something regarding breaking weapons?
MC5 said:Striking it with physical weapons is like hitting a granite boulder. Edged weapons cause only half damage and must roll saving throws vs. crushing blow.
this passage should help illustrate why I don’t think a physical attack is necessary:
MC5 said:The horgar is not an aggressive creature. The main problem is that it does not recognize most living creatures, at all. If unprovoked, it goes its own way, whether or not somebody is in the way. If attacked, it tries to leave.
if we give it anything, it should not be terribly damaging. The slime and heat should take care of most attackers, and if it comes up against something that is immune to acid and fire, then that is its problem.

finally wrote up the flavor text:
This appears to be a cooled-down, oblong lava formation at first. It begins to move, giving it the appearance of a slug made from black granite. Even at a distance, the heat generated by this creature is intense, and its acidic odor of ammonia is powerful.
The horgar is an immense, powerful creature that eats its way through solid rock to create subterranean tunnels, passageways, and caverns. It lives deep within the earth, spending all of its time tunneling through and eating rock.
Some races call this creature a stone-eater, though it is commonly known by its dwarven name of horgar, and its less commonly known gnomish name of storgin (both of which mean “stone-eater”). These mysterious creatures are sometimes worshipped as gods by primitive lesser races. Some races try to tame horgar, to use the creatures to make passageways as they want and to attack enemies. Such captive horgar are kept in glass-lined pits, and their keepers (called horgarin in the Dwarf tongue) slip long, thin spears through the cracks in their skin to prod the sensitive flesh below. Thus, a horgarin may control which direction a horgar moves, though a careless handler is likely to lose his life to his charge.
A horgar’s chitinous skin is made from five-foot thick stone, with great cracks that divide it into large plates. These plates shift and slide while the creature moves, creating small fissures from which the horgar secretes its super-heated slime. A horgar also constantly generates searing heat from its body, reaching between 400 and 500 degrees. As a horgar moves, it grinds against the tunnel walls it makes, as its slime and heat melt the rock and fuse it into new formations. The only exposed part of a horgar is its round head, located at one end, which just seems to be a lump of softer-looking stone.
It is easy to detect a fresh stone-eater tunnel, as it remains hot for many hours. Tunnels and other new formations cut through hard rocks such as granite remain permanent, while passages made in softer stone such as sandstone collapse as the horgar moves through them.
A horgar is at least 30 feet long and can grow up to 100 feet in length, and weighs X tons.
COMBAT
A horgar is not an aggressive creature, by any stretch of the imagination. A horgar does not recognize most organic things as living creatures, and tends to continue moving whether or not something is in the way. If provoked or attacked, a horgar will usually try to leave. If it cannot run away, a horgar will turn to fight. It can squirt acid from its head up to 20 feet away. It will try to flee again at the first available opportunity.