The Mavora were psychic predators which apparently fed on and were fuelled by lies, but also appeared to like the taste of fear. They resembled large squares made of energy with faces, and varied in colour. The Mavora existed in only two dimensions, and therefore they could slide between the atoms of the universe but had some difficulty navigating through physical space. They could also devour and kill victims, reducing them to bones and ash in the process, simply by passing through them.
A large number of Mavora were imprisoned in The Sorrows of Prague, and so in 1989, Yuri Azarov and another Mavora worked to find the book and free the trapped Mavora. They eventually retrieved the book and freed the Mavora imprisoned inside. (COMIC: The Broken Man)