The official GemStone IV encyclopedia.
A towering, animated, glass-like creature, the huge mein golem is comprised entirely of mein. Taller than a giantman by half again and nearly as wide as tall, the mein golem displays a barrel chest, massive legs and arms, and a flattened, cylindrical head with almost no neck apparent. Animated by someone with a unique sense of humor, the huge mein golem contains many surprises for the unwary adventurer.
Seems impossible or very difficult to knock over. Tremors(909) and E-Wave(410) seemed to have no effect.
Seems immune to 901. (Message says it "reflects" the attack, but it doesn't actually go back to you.) Other bolt spells worked fine and they have low bolt DS.
Searching will cause it to explode in a maneuver attack a couple of seconds later. (No treasure?)
Seems immune to crits.