The Triangle of Terror

The Triangle of Terror is a group of three archdemons.

Edowir says the following about it:

The Triangle of Terror is a cabal of three archdemons that have put aside their quarrels to establish some power in the shadows of the Ruthless Seven. Although they are all very mighty demons, compared to one of the seven, they appear weak. So they try not to interfere much with the doings of the seven and look for power elsewhere. Their members are Morgaroth, the schemer, Ghazbaran, the lord of blades and Zoralurk, the demon with the thousand faces.