When he senses someone attempting to escape or infiltrate the underworld, the usually stone Balaur flies into a violent rage and seeks to destroy the perpetrator. There is no escaping his wrath.
In Romanian folklore, the Balaur is a creature similar to a dragon. A balaur is quite large, has fins, feet, and is polycephalous (it usually has three, sometimes seven, or even twelve serpent heads). As a traditional character which is found in most Romanian fairy tales, it represents Evil and must be defeated by Făt-Frumos in order to release the Princess. Balaur seems to derive from Proto-Indo-European language words *bel-, "strong", or *bhel-, "to swell". It is considered to be a pre-Roman conquest word from the Romanian substratum.