As illustrated in the Shadowhunter's Codex.[1]
A Raum is a demon whose most dangerous weapon is its tentacles—slick, gray-white, and tipped with red suckers, each of which contains a cluster of tiny, poisonous needle-like teeth. Their poison is slightly more complex than a Drevak sting but is still manageable.
Description
Intimidating and dangerous, Raum demons are clever opponents despite being incapable of speech and generally unintelligent. Raums are the size of an elongated human and possess white, scaled skin, bulging black, toad-like, pupil-less eyes, a perfectly circular mouth. Raums make distressed, hooting noises, move incredibly fast and are known to be retriever demons.
History
Valentine Morgenstern once summoned Raum demons and sent two of them to Luke's home to retrieve the werewolf Maia Roberts. They attacked Luke on his lawn and knocked him out, bringing him to the waterfront across the street from his house. Jace's Sensor detected their presence, and Clary noticed their movement by the bank of the East River. Jace tortured one, threatening to strike its heart, which Valentine taught him when he was young, to tell him Valentine's location, and the other escaped into the river just as Clary drew her seraph blade to fight it. Luke then realized that the demon might still be looking for Maia.
There were also Raums among the myriad of demons summoned and kept aboard Valentine's ship.
Weeks later, while walking up to Luke's house, Clary reminisced with Simon their first encounter with the demons.