An exceptionally fierce individual, she was perpetually angry and constantly hunting for prey, be it Orc or Dwarf. Thus, she was rarely at her lair in Irerock above Wolf Flat, a huge multistoried cavern-maze located ten miles north of the northernrim of the Heath. Known for her greed and unwavering hatred for the neighbouring Dwarves, Leucaruth coveted their riches and was soon attracted by the growing power of Sauron in the mid-Second Age. Welcomed among his servants, she was commanded into troubling the holds of the Longbeards. But the arrival of the Numenóreans pushed her back to Irerock, where she remained until Sauron's return.
Part of Sauron's strategy to strengthen his hold over the North in the War of the Last Alliance, Leucaruth sacked the fabled halls of Thrumfall and forced the Dwarves out, collapsing the main entrance on her way out. As offered, the Dark Lord allowed her to keep the stolen treasure hoard and futhermore promised to grant her lordship of the North once he ruled all of Middle-earth. With the end of Sauron's dominion at the war's end, Leucaruth evaded the victors' ire and was left to her old devices.
In the Third Age, Leucaruth joined the other Dragons of Forodwaith in waging war against the Dwarves, lying waste to their underground dwellings and leaving everything in ruins. She notably slew Úri, but failed to destroy his Ring, which was claimed by Kuri. Having sated her wrathful tendencies and amassed sufficient wealth, the Dragon returned to Irerock, troubled only by travellers too curious for their own good. Her final fate remains unsettled but she was widely believed to be dead by the time of Thorin and his company's quest to reclaim Erebor.
- MERP:Creatures of Middle-Earth
- MERP:The Grey Mountains
- the Lord of the Rings Role-Playing Game: Dwarves of Middle-Earth (Moria Boxed Set)