Black Knights
Hell-spawned spirits clad in huge, elaborately decorated suits of plate mail armor: Black Knights are aggressive, mercilessly tenacious guardian creatures, whose glowing red eyes betray their demonic origin.
Ecology and behavior
These constructs are made by luring malevolent spirits from the underworld, trapping them within enchanted suits of armor. Once bound by the armor's magic, the spirits have no power to resist the commands of the summoner, and they are bound to his service until released or until the enchantments engraved on their armor are physically broken.
Habitat
Black Knights are elite soldiers in the armies of Prince Malaut. They stand guard over his temples, serve as bodyguards to his priesthood, and champion the faith against its many enemies. Malaut's followers, called the Twilight Empire, are currently active only in the human kingdom of Mercia, but the ambitions of the Red Prince are global in scope.
Black Knights are mostly found in or near the inner sanctums of Twilight Empire coteries, providing muscle for the spellcasting Below that summoned and bound them.
The spirits bound within the Black Knights' armor are natives of the Shadelands, Malaut's native, subterranean realm, which lies more or less directly underneath the Mercian heartland.
Variations
Though the same size as Black Knights, Black Lords are made using more powerful binding enchantments, which allow Malaut's priests to trap stronger spirits. Physically more or less identical to Knights, Black Lords fight using twin axes instead of swords.