Wuxian (无限 Wúxiàn, lit. "infinite") is Luo Xiaohei's master and the deuteragonist of The Legend of Hei. He has a calm demeanour and initially, is seen as cold and unsympathetic. However, his caring nature is revealed later in the film.
Wuxian is capable of manipulating all types of metal, which he ends up teaching to Xiaohei. Through the ability 'Devour', Wuxian is able to create large holes that 'devour' all surrounding objects/materials.
(Source: The Legend of Hei Fandom, on luoxiaohei.fandom.com)