When Mhaldor was founded centuries ago, a cabal of black-magic, Chaos-driven wizards and warlocks founded the magic school of Um Loran. This was in part due to the establishment of Thyckletray as well as an attempt to strong-arm the black wizards into some sort of order.
Um Loran is a brutal school where over half of its students do not survive the training or are left as shattered, broken failures, pressed in indefinite service to the school to pay for their failure. It is said that the cabal of wizards who lead Um Loran also rule over Mhaldor.
Those magic-users who bear the signet ring of Um Loran are feared and despised in the lawful lands of Men. Those rings are prized possessions and any who possess a ring without having earned it will soon find themselves haunted and hunted by agents of Um Loran, seeking to take back the ring. It is not known why the rings are so significant.