Source: Bestiary, pg(s). 94
Guthallaths are enormous stone constructs embedded in the earth that, very rarely, will activate and go on rampages of destruction.
A guthallath resembles a giant stone warrior. The constructs typically reach over 100 feet tall and all share a close resemblance, indicating that they were all created by the same ancient civilization.
Not only does a guthallath have tremendous physical strength, but they also are typically largely immune to normal magical attacks. Guthallaths are surrounded by auras of destruction, physically degrading their surroundings. Finally, if their size, strength, and very presence are not enough to destroy their targets, the guthallath also can release rays of intense, destructive energy from its eyes. Typically, the only thing that will stop a guthallath is the guthallath itself.
For the overwhelming majority of the time, centuries even, guthallaths are simply ancient monuments half-buried in some remote location. Only when some unknown trigger occurs do the constructs carry out their brutal duties. Entire countries have been destroyed by one of these shockingly agile giants, and a guthallath will usually only return to slumber after some esoteric condition is met.