From Unofficial Handbook of the Virtue Universe
Most beings know nothing about this demon beast... and those that do, speak of it with hushed tones. Xyr'rexian's appear as monstrous and horrendous Manta-like beings with jagged scales, bony spines, and razor teeth. Wherever they travel, the sea grows darker, and nearby, smaller sea life dies (plants, smaller fish, etc) Even larger, and even intelligent creatures can feel the tug on their life force in these creatures presence.
This Demon was first discovered, when the Titans warred with their childer Gods. It is believed they were foot soldiers for the Titans, and took many shapes in the past... Some Legends claim that they grow larger over time, and that trully ancient Xyr'rexian's can be colossal... though only those of the above description have ever been discovered, and even then, in the deepest, and darkest recesses of the sea.
The Xyr'rexian's are extremely intelligent, and each is a powerful caster of the blackest magics. They command an arsenal of powerful supernatural abilities.
No one knows how long they live, or how they reproduce. They speak their own language, but most know many, many more. They are extremely durable and even, regenerative, if they have uncorrupted material to consume. Stories speak of them feeding off of magical energies, and consuming casters incantations directed at them! Xyr'rexians prefer to operate behind the shadows, and rarely ever leave the darkest areas of the sea, as natural light causes them extreme agony.
There is a legend of a brave Mer scholar who faced one in a duel of riddles for his eternal soul, he defeated the creature, but it turned upon him anyway. The Legend states that he banished the creature back into the darkness, by presenting it a gift to appease its hunger... a mirror. The Creature fled from its own reflection.