Sight Beyond Sight is a status "ailment", gained through the Cyclops Eye Soup, that reveals all aspects of each level of the Caverns of Creation. Dwarf Hammer, like all rogue-like games, gradually reveals portions of each level as the player moves through it. Sight Beyond Sight reveals the entire layout, all creatures including invisible ones (but not the ceiling-clinging drop bear), all treasures, and all traps for the duration of the effect.
The effect is not present in Dwarf Mallet. Proponents argue that this makes it more of a fair challenge; purists laugh at them.