Tales of the Bloodstone Lands
This creature looks like a starfish atop 5 mechanical legs.
Pentadrone 1298 was discovered guarding an Abyssal ruin known as the Slaughtergarde Laboratory. It explained that the Demon Lord Mu-Tahn Laa had brought his Abyssal fortress Slaughtergarde to the world of Toril and it was part of the forces arrayed against the demon lord.
This modron was called from the plane of Mechanus by the celestial army for the battle that ended with Slaughtergarde’s destruction. In the middle of the battle, the modron was ordered to guard this chamber against summoners that might arrive and call demons using the summoning circles. That was centuries ago (“186 revolutions of this sphere around its star” to be exact, which the modron is). The modron is still waiting, and it continues to follow its orders until a superior officer—now long gone to Mechanus —relieves it of duty.
Not a mindless automaton, the modron is conscious that centuries have passed, and it’s keenly aware that no battle seems to be afoot. But it’s endlessly patient, and recent clashes with the goblins have led it to suspect that the demons are returning.
The modron is a patient if somewhat machinelike creature.