Merlock, also known as Merlock the Magician, is or was an anthropomorphic wolf and Merlock's counterpart in the 2017 Continuum.
Merlock is or was a dark sorcerer of immense power and lore. At some point before 2017, he wrote a spellbook collecting some of the spells (both good and evil) that he had come to learn as a scholar of magic: The Grimoire du Merlock.
Behind the scenes
This version of Merlock was mentioned in the 2018 DuckTales 2017 episode, JAW$, with Webby apparently possessing his spellbook.
Francisco Angones has left open the possibility that Merlock may have an on-screen role in the series
↑(Which he could arguably have published, making Webby's book only one of hundreds of copies.)