Crystal golem

A crystal golem was a golem constructed of magically animated pieces of crystal.

Description
These golems often served powerful nobles, who were also spellcasters or hired those with the ability to do so. As per typical golems, they were willing to fight their master's adversaries without care for their own lives. Although crystal golems looked fragile, owing to being made of crystals, they were surprisingly resilient. Weakened or damaged golems could be identified by large crisscross patterns across their crystalline bodies. They made brilliant long-range guardians, but, while being more dexterous than most golems, they lacked brute strength.

Combat
Such golems relied on terrain and ranged attacks to defeat their foes. Mages who animated crystal golems often paired them with melee constructs, so the crystal golems could stay out of range and cast powerful attacks. These attacks consisted of firing piercing crystal shards and crystalline darts at one or more opponents. They only attacked enemies with their natural strength when cornered or when forced to fight at close range. When on the brink of death, these golems would release all of their energy in the form of crystal shards, inflicting high damage to a large number of opponents.

Crystal golems had hardy and sharp-edged outer layers, which could splinter if hit, causing the shards to embed into an opponent's flesh. As well as their tough bodies, they were immune to both disease and poison.

Notable Crystal Golems
The Crystal Labyrinth level of Undermountain harbored crystal golems that resembled tall githyanki. These constructs attacked anyone that didn't look like either a githyanki or a red dragon on sight.