Rockguts are what happens when the mountains lose patience. Quarried-looking brutes with hides of living stone, they wade through arrow-storms unbothered and shed hostile magic like rain off a cliff-face, spells sputtering out against skin that geology claimed first. Each carries a boulder or two, hurled flat and hard enough to unmake a knight and the horse beneath him.
Thought comes slowly to a Rockgut, and violence arrives well ahead of it. They follow the Bad Moon's gloom by pure instinct, trudging after the dark the way plants lean toward light, and wounds that should kill them simply close, flesh and stone knitting while the troggoth wonders vaguely what stung. A mob of them will walk through a fortress wall and forget the fortress before the dust settles.